BoxBolt vs. Hollo-Bolt : Which Blind Bolt Is Right for Your HSS Connection?
When engineers need to make a blind connection into hollow structural steel, two products come up consistently in specifications: BoxBolt by LNA Solutions and Hollo-Bolt by Lindapter. Both are well-engineered, ICC-approved solutions for HSS connections. Both eliminate the need for through-bolting or welding. Both are trusted on major projects.
So how do you choose between them?
This comparison breaks down the key differences based on published catalog data from both manufacturers. No speculation, just the specs that matter for your application.
Not sure which blind bolt is right for your project? Talk to an LNA engineer
What they have in common
Before getting into differences, it’s worth noting what both products share. Both BoxBolt and Hollo-Bolt are single-side access blind bolt systems designed specifically for hollow structural steel members. Both require pre-drilled holes. Both are ICC-ES approved for seismic applications. Both are available in carbon steel and stainless steel. Both are recognized by AISC.
If either product is on your approved list, you’re working with a product that has been independently tested and code-evaluated.
ICC approval numbers
This is the first thing a structural engineer should check for any code-compliant project.
- BoxBolt: ICC ESR-3217 (Acceptance Criteria AC437)
- Hollo-Bolt: ICC ESR-3330
Both approvals cover seismic applications. BoxBolt’s ICC Type C designation is specifically engineered for HSS-to-structural steel connections with static dominant lateral loads in slip-critical conditions. Hollo-Bolt’s ESR-3330 covers all Seismic Design Categories A through F per IBC.
For projects requiring a specific ESR number in the contract documents, confirm with your AHJ which approval is referenced.
Available sizes
BoxBolt is available in six diameters: 1/4″, 5/16″, 3/8″, 1/2″, 5/8″, and 3/4″. Body length and finish availability varies by diameter. Zinc plated and hot-dip galvanized are offered in Size 1, Size 2, and Size 3 from 5/16″ through 3/4″. Stainless steel is offered in Size 1 and Size 2. The 1/4″ diameter is offered in Size 1, in zinc plated or stainless steel.
ICC Approved BoxBolt Type C is supplied hot-dip galvanized in 1/2″, 5/8″, and 3/4″ diameters, in Size 1, Size 2, and Size 3.
Hollo-Bolt is available in five bolt diameters: 5/16″, 3/8″, 1/2″, 5/8″, and 3/4″. Each diameter also comes in three clamping range options.
BoxBolt’s 1/4″ (M06) option gives it a smaller starting size, which can be relevant for lighter gauge applications or space-constrained connections.
Head styles
This is where the two products differ most visibly.
BoxBolt has a single head style, a hexagonal shoulder that sits flush against the HSS face.
Hollo-Bolt offers three head styles:
- Hexagonal Head – standard visible protrusion
- Countersunk Head – minimal visible protrusion
- Flush Fit Head – zero visible protrusion
If architectural finish matters in exposed steelwork in a public space, stadium, or curtain wall application, Hollo-Bolt’s countersunk and flush fit options give specifiers more flexibility. For structural connections where the bolt head is not visible or aesthetics are not a consideration, both products perform the same function.
Finishes available
- BoxBolt: Zinc plated, Hot-Dip Galvanized (HDG), Stainless Steel
- Hollo-Bolt: Zinc Plated + JS500, Hot-Dip Galvanized, Sheraplex, Stainless Steel (316 equivalent)
Hollo-Bolt’s Sheraplex finish is an additional corrosion protection option not available on BoxBolt. For aggressive environments where stainless steel is over-specified but standard galvanizing is under-specified, that extra option has value.
For most structural applications, zinc plated or HDG will be the spec. Both products offer identical options at that level.
Certifications beyond ICC
BoxBolt:
- Lloyd’s Register Type Approval
- DIBt (Deutsches Institut fur Bautechnik)
- ICC ESR-3217
Hollo-Bolt:
- ICC ESR-3330
- Fire tested per ASTM E-119 (up to 120 minutes, F120) – carbon steel hexagonal head
- Evaluated for fatigue resistance per AISC 360 Appendix 3 – carbon steel hexagonal head
- Low temperature tested to -50 degrees F
Hollo-Bolt’s fire rating and fatigue evaluation are meaningful for specific applications, particularly transportation infrastructure and projects with explicit fire resistance requirements. BoxBolt carries Lloyd’s Register Type Approval and DIBt certification, which carry particular weight in marine, offshore, and international project specifications.
The approvals listed above are those referenced in the source documents cited at the end of this article. Neither list is exhaustive. Both manufacturers hold additional certifications, and engineers should confirm current approval status directly with the manufacturer and against the governing code for their jurisdiction.
Need help verifying which certification your project requires? Contact LNA
See BoxBolt installation in action
BoxBolt installs with basic hand tools from a single side, no drilling, tapping, or welding required. Watch the full installation process below, or read our step-by-step BoxBolt installation guide for detailed written instructions.
Installation tool
BoxBolt has the BoxSok, a dedicated rapid assembly tool available in all six bolt sizes that holds the hexagon shoulder during tightening, enabling faster installation with an impact wrench or ratchet.
Hollo-Bolt has a plug-in tool available in Tekla Warehouse for BIM modeling.
Both products install with basic hand tools. The BoxSok is an optional speed accessory for high-volume installation.
Quick reference comparison
| BoxBolt (LNA Solutions) | Hollo-Bolt (Lindapter) | |
|---|---|---|
| ICC Approval | ESR-3217 | ESR-3330 |
| Seismic rating | Type C | SDC A through F |
| Sizes | 1/4″ to 3/4″ | 5/16″ to 3/4″ |
| Head styles | 1 (hexagonal) | 3 (hex, countersunk, flush fit) |
| Finishes | Zinc, HDG, SS | Zinc+JS500, HDG, Sheraplex, SS |
| Fire rating | Not applicable | F120 (ASTM E-119, hex head) |
| Fatigue evaluation | Not applicable | AISC 360 App. 3 (hex head) |
| Approvals cited in this article | Lloyd’s Register Type Approval, DIBt, ICC ESR-3217 | ICC ESR-3330, ASTM E-119 fire, AISC 360 App. 3 fatigue |
| Installation tool | BoxSok | Tekla plug-in |
| U.S. supplier | LNA Solutions (Buffalo, NY) | Lindapter |
Which one should you specify?
There’s no universal answer, both are well-engineered products. Here’s a practical way to think about it.
Consider BoxBolt when:
- Your project requires Lloyd’s Register Type Approval or DIBt certification
- You need a 1/4″ blind bolt for lighter gauge HSS
- You’re doing high-volume installation and want the BoxSok speed advantage
- You’re sourcing domestically from a U.S.-based supplier with U.S. stock
Consider Hollo-Bolt when:
- Your project has explicit fire resistance requirements (F120)
- You need a flush or countersunk head for architectural finish
- The project references ESR-3330 specifically in the contract documents
- You need fatigue evaluation per AISC 360 Appendix 3
For most standard structural HSS connections, either product will perform. The decision often comes down to which ESR number is on the project spec, your regional supplier relationship, and whether any of the distinguishing features above are project requirements.
Ready to specify BoxBolt? Get a quote from LNA Solutions
Not sure which product fits your project?
Our engineering team is available to review your connection requirements and recommend the right solution. We offer free technical support for specifiers, including connection detailing, load verification, and project-specific product recommendations.
You can also find your local LNA representative for in-person support.
Talk to an LNA engineer about your HSS connection
A note on technical verification
BoxBolt certifications and specifications in this article are sourced from the LNA Solutions 2024 Steel Connection Solutions Catalog. Hollo-Bolt information is sourced from Lindapter’s published product documentation and ICC-ES evaluation report ESR-3330. Approval lists are not exhaustive and are current as of the review date shown above.
For connection design, always refer to the current ICC-ES evaluation reports (ESR-3217 and ESR-3330), confirm current approval status with the manufacturer, and consult a licensed structural engineer.
Related reading
- BoxBolt product page
- How to install BoxBolts: step-by-step guide
- How to connect hollow structural sections from one side
- Find your local LNA representative
- Request a quote
Frequently asked questions
What is the difference between BoxBolt and Hollo-Bolt?
BoxBolt and Hollo-Bolt are both single-side access blind bolts for hollow structural steel connections. Key points of difference: BoxBolt carries Lloyd’s Register Type Approval and DIBt certification and is offered in a 1/4″ diameter; Hollo-Bolt offers three head styles (hexagonal, countersunk, flush fit), a fire rating of F120 per ASTM E-119, and fatigue evaluation per AISC 360 Appendix 3. BoxBolt is ICC ESR-3217 approved; Hollo-Bolt is ICC ESR-3330 approved.
Is BoxBolt ICC approved for seismic applications?
Yes. BoxBolt Type C is ICC ESR-3217 approved and is specifically engineered for HSS-to-structural steel connections with static dominant lateral loads in slip-critical conditions, with a modified design to resist seismic loads.
Can BoxBolt be used instead of Hollo-Bolt?
In most standard structural HSS connection applications, yes. Both products are ICC-ES approved blind bolts for hollow structural steel. The decision typically comes down to which ESR number is referenced in the project contract documents, certification requirements, and whether specific features such as flush fit head styles or fire ratings are required.
What certifications does BoxBolt have that Hollo-Bolt does not?
BoxBolt holds Lloyd’s Register Type Approval and DIBt (Deutsches Institut fur Bautechnik) certification, in addition to ICC ESR-3217. Lloyd’s Register Type Approval carries particular weight in marine, offshore, and international project specifications. For the current approvals held by any competing product, refer to that manufacturer’s published documentation.
Where can I buy BoxBolt in the United States?
BoxBolt is supplied by LNA Solutions, based in Buffalo, NY. LNA Solutions has been serving the U.S. structural steel market since 1995. You can request a quote or find a local representative at lnasolutions.com.
BoxBolt is a registered trademark of LNA Solutions. Hollo-Bolt and Lindapter are registered trademarks of Lindapter International Ltd. LNA Solutions is not affiliated with, sponsored by, or endorsed by Lindapter International Ltd. Trademarks are used here for identification and comparison purposes only.
Last reviewed: September 2, 2026
