Designed
With
Consequence.
Every detail of every BOTA product exists for a reason. The mail slot is not a decorative element. It is a functional opening in a structural threshold. It deserves to be treated accordingly.
Brass-Seal™
Forged Brass
Mail Slot System
An exterior and interior system engineered from solid forged brass. Independently tested under ASTM E283 by Intertek. Built for the specification demands of high-end residential and commercial projects where material integrity and performance are held to the same standard.
View Brass-Seal™ →BOTA Mail
Slot
Insulator
An interior retrofit solution that works from within the mail slot cutout. First in category to expand horizontally and vertically. Tool-free installation. London Design Awards Gold 2024. A precision upgrade that works with virtually all existing mail slot designs.
View Insulator →01
Material Integrity
Every material in a BOTA product is chosen for longevity under real conditions. The entry threshold is subject to daily use, weather, and temperature change. The materials must be equal to that.
02
Controlled Closure
Gravity is not a closure mechanism. BOTA products use engineered closure: calibrated in the interior forged brass unit, and heat-resistant magnetic closure in the exterior. The opening is managed, not left to chance.
03
Considered Fit
The BOTA Mail Slot Insulator is the first in its category to expand both horizontally and vertically, accommodating virtually all existing mail slot cutout sizes without modification to the door. Available in letter and magazine sizes.
04
Full-Depth Performance
Air and sound do not stop at the exterior flap. They move through the full thickness of the door. BOTA addresses the opening at both faces: exterior hardware and interior solution. The result is the most complete available.
05
Safe by Design
A mail slot is an unguarded opening. The steel closure bar in the BOTA Mail Slot Insulator serves a dual purpose: it attracts to the magnets at the base of the unit to maintain a secure, repeatable closure, and it places a physical barrier between the mail carrier and the interior of the home.
06
Verified Performance
Claims are not sufficient. The Brass-Seal™ system is independently tested under ASTM E283 by Intertek — both the exterior and interior units, tested standalone and as a paired system. Results are on file. Performance is documented, not stated.
An interior solution built
to work within the door.
The BOTA Mail Slot Insulator is positioned within the existing mail slot cutout. No modification to the door required. Its adjustable frame expands to fit, its closure mechanism engages with each use, and its construction is chosen for resilience over time.
Mail Slot Insulator / Letter Size / Interior Side
Engineered to Close
The acoustic flap conforms to the exact cutout shape of the mail slot opening. The process takes a few hours. After that, it performs identically every time.
Built for Longevity
The insulation compound used in the BOTA Mail Slot Insulator is a custom blend developed for durability in demanding environments. It does not compress, crack, or degrade under the conditions a mail slot faces across years of seasonal change.
Protected on Both Sides
The steel closure bar addresses what the exterior flap does not: what happens on the inside of the opening. It attracts to the magnets at the base of the unit for a secure, repeatable closure. It also places a physical barrier between the mail carrier and the interior of the home. The opening is managed in both directions.
First in Category
No other mail slot insulator expands both horizontally and vertically. The BOTA insulator adjusts to the cutout. Not the other way around. Available in letter and magazine sizes. Retrofits existing hardware and installs without tools in minutes.
Forged brass.
Verified performance.
The Brass-Seal™ system is the exterior expression of the same engineering philosophy. Where the insulator works from within, the Brass-Seal™ addresses the entry from the door surface, with a material and a standard equal to the hardware it accompanies.
Brass-Seal™ / Letter Size / Satin Brass / Open
Forged Brass
Not plated. Not cast. Solid forged brass throughout. Chosen for its density, its surface character, and its proven performance at architectural thresholds.
Heat-Resistant
The exterior unit uses a heat-resistant magnetic closure, engineered to perform across the temperature range the front door faces through every season.
Calibrated
The interior forged brass unit uses a calibrated closure: a precise, repeatable mechanism that manages the opening consistently over years of daily use.
ASTM E283
Independently tested under ASTM E283 by Intertek, the industry standard for air infiltration through building components. Performance results on file for specification review.
Pending
Proprietary engineering developed exclusively by BOTA. The Brass-Seal™ system is patent pending.
Bonded at the Molecular Level
PVD (Physical Vapor Deposition) is a process that bonds a thin, dense layer of finish directly to the brass substrate at the molecular level. Unlike plating or paint, PVD does not sit on the surface. It becomes part of it. The result is a finish that resists wear, tarnish, and corrosion without degrading over time. Available in Satin Brass, Satin Nickel, and Satin Black. All visible components including screws and hinge pins finished to match.
The insulator installs
in minutes.
No tools required.
The BOTA Mail Slot Insulator is designed for straightforward installation. No modification to the door. No hardware. The adjustable frame sets the fit; the insulator does the rest.
Questions about installation?
We are here to help.
- 01 Interior plate removal (if needed). If the interior mail slot plate blocks access to the door cutout, remove it and set it aside for reinstallation.
- 02 Install the adhesive-backed perimeter foam into the existing mail slot cutout. Foam is supplied long to fit a range of sizes. Trim excess only after installation is complete.
- 03 Remove the Velcro-backed closure bar and set aside. Place the insulator into the mail slot opening in its unexpanded state. Expand horizontally then vertically until firm against the perimeter foam with no movement and no air gap.
- 04 Install the C-Clip. Select the clip that matches the opening created during expansion and snap it into place to secure the width.
- 05 Final assembly and check. Attach the Velcro-backed closure bar to the bottom edge of the flap so the steel rod engages with the magnet. Confirm the flap opens freely and closes fully with no air gaps.
Three steps.
Matching PVD screws included.
The Brass-Seal™ Forged Brass Mail Slot installs using the included template and hardware. A Phillips screwdriver is all that is required.
Questions about installation?
We are here to help.
Download Instructions:
Brass-Seal™ Mail Slot / English & Spanish (PDF)- 01 Position the included template level and centered around the door cut-out. Mark screw holes and drill 7/64" (2.778mm) pilot holes.
- 02 Secure the mail slot with the provided screws using a Phillips screwdriver. All visible components including screws and hinge pins are finished to match.
- 03 Confirm the flap opens freely and the magnetic closure engages fully. Polish with a soft cloth. Do not use abrasive cleaners.
The Standard Was Set Here.
Two products. One standard of precision. Specification documentation, press assets, and material samples available for architects, designers, and editors.
Shop Products Request Information