For Contractors & Installers
A Clean Install. A Verified Result.
The Brass-Seal installs with standard tools - ASTM E283 verified performance your customers can document. The Mail Slot Insulator installs tool-free. No callbacks, no maintenance required once installed.
Two Products.
Every Standard Application Covered.
The BOTA line covers the full range of standard residential mail slot scenarios. The Brass-Seal is available in Brass-Seal Exterior and Brass-Seal Interior configurations, each in Letter and Magazine sizes - all independently verified under ASTM E283. The Mail Slot Insulator retrofits the existing cutout tool-free.
| Product | Size | Outer Dimensions | Opening | Installation | Performance |
|---|---|---|---|---|---|
| Brass-Seal Exterior Standalone or paired system |
Letter | 9.88" × 3.76" | 8.00" × 2.25" | Standard drill and screwdriver. Template included. | ASTM E283 Verified · Intertek · Patent Pending |
| Magazine | 13.26" × 4.01" | 11.375" × 2.50" | |||
| Brass-Seal Interior Standalone or paired system |
Letter | 9.88" × 3.76" | 8.00" × 2.25" | ||
| Magazine | 13.26" × 4.01" | 11.375" × 2.50" | |||
| Mail Slot Insulator Flap must open outward |
Letter & Magazine | Fits most standard cutouts | Tool-free. Clicks apart to fit. | London Design Award Gold · 2 Patents | |
ASTM E283 Results.
All Configurations.
Independent test results from Intertek Building and Construction. All three Brass-Seal configurations tested and verified under ASTM E283/E283M-19 at 75 Pa. Full report available upon request at info@blockouttheair.com.
| Configuration | Test | Result | Allowable Max | Status |
|---|---|---|---|---|
| Interior (standalone) | Air Infiltration · 75 Pa | 0.6 L/s/m² (0.12 cfm/ft²) | 1.5 L/s/m² (0.3 cfm/ft²) | PASS |
| Interior (standalone) | Air Exfiltration · 75 Pa | 0.3 L/s/m² (0.06 cfm/ft²) | 1.5 L/s/m² (0.3 cfm/ft²) | PASS |
| Exterior (standalone) | Air Infiltration · 75 Pa | 1.0 L/s/m² (0.20 cfm/ft²) | 1.5 L/s/m² (0.3 cfm/ft²) | PASS |
| Exterior (standalone) | Air Exfiltration · 75 Pa | 0.6 L/s/m² (0.11 cfm/ft²) | 1.5 L/s/m² (0.3 cfm/ft²) | PASS |
| Paired System | Air Infiltration · 75 Pa | 1.0 L/s/m² (0.20 cfm/ft²) | 1.5 L/s/m² (0.3 cfm/ft²) | PASS |
| Paired System | Air Exfiltration · 75 Pa | 0.6 L/s/m² (0.11 cfm/ft²) | 1.5 L/s/m² (0.3 cfm/ft²) | PASS |
Intertek Building & Construction · Report No. T4376.01-301-44-R1 · April 2026 · Test pressure: 75 Pa (1.57 psf) · Full report available upon request at info@blockouttheair.com
Standard Tools.
Precise Fit.
The Brass-Seal installs with a standard drill and screwdriver. A precision drill template is included with every system.
Letter Size Outer: 9.88" × 3.76" · Opening: 8.00" × 2.25"
Magazine Size Outer: 13.26" × 4.01" · Opening: 11.375" × 2.50"
Included with every Brass-Seal™ system. Available in advance at no charge - ships via USPS in 2-3 business days. Request in advance
A Clean Add-On.
Zero Callbacks.
The Brass-Seal adds value to any weatherization, weatherproofing, or energy efficiency job. It is a set-and-forget product - once installed, there is nothing to fail, adjust, or maintain. The ASTM E283 test result gives your customers documented, third-party verified performance.
- No Maintenance Required - No callbacks. The EPDM gaskets and polyurea-lined cavity provide a continuous seal once installed.
- ASTM E283 Verified (Brass-Seal) - Your customers get a product with a third-party tested result they can put in writing.
- Precision Drill Template - Included with every Brass-Seal system. Available in advance at no charge, ships in 2-3 business days. Request in advance.
- Two Products, Full Coverage - Brass-Seal Exterior and Brass-Seal Interior, each in Letter and Magazine sizes, all ASTM E283 verified. Mail Slot Insulator for tool-free retrofit when the flap opens outward. The Brass-Seal Interior also completes the paired system alongside the Brass-Seal Exterior.
- Historic and Landmark Properties - The Brass-Seal Interior preserves the existing exterior hardware. No alteration to the door face.
- Savings Documentation - The BOTA savings calculator produces a ZIP-matched PDF estimate of energy savings for your customers.
Downloads.
Installation guides, drill templates, and performance documentation for the job site or your records.
| Document | Product | Download |
|---|---|---|
| Installation Guide | Brass-Seal | Download PDF |
| Drill Template - Letter Size | Brass-Seal | Download PDF |
| Drill Template - Magazine Size | Brass-Seal | Download PDF |
| Installation Guide - English | Mail Slot Insulator | Download PDF |
| Installation Guide - Spanish | Mail Slot Insulator | Download PDF |
Contractor & Trade Inquiries
For volume orders, trade pricing, project-specific guidance, or questions about installation, reach out directly. We support contractors, weatherization firms, energy retrofit specialists, and property managers.
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