The Original Self-Sealing Fasteners

The Original: Self-Sealing Fasteners from APM Hexseal

APM Hexseal® holds the notable distinction of having designed and patented the very first self-sealing fasteners, which later became their trademarked Seelskrews® and Seelbolts®.

It wasn’t long before they developed other sealing hardware, like their self-sealing Seelnuts® and Seeloc® Washers. In addition to providing a strong, reliable seal against all manner of contaminant(s), APM Hexseal’s wide range of hardware products are designed for easy installation and equally easy removal and reuse.

Types of Sealing Hardware

Seelskrews & Seelbolts

A Seelskrew diagram demonstrating the O-ring beneath the head

Designed to prevent contamination from all types of substances. They are vibration resistant and can be used in applications that encounter jarring or repetitive movements. Available in a number of sizes and can be customized for specific application needs.


A diagram of a Seelnut showing the rubber essentially molded into the base of the nut itself

Made from high quality rubber, and then molded into a specially shaped cavity within the nut itself. Designed for applications that involve high internal or external pressures. They are also reusable, meaning that they can be easily removed and reapplied.

Seeloc Washers

A diagram of a Seeloc Washer demonstrating how the gasket covers the entire base and hole of the washer

Seeloc washers consist of molded silicone rubber bonded to specially formed stainless steel washers. Their design creates a 360 degree sealing barrier around the periphery of the washer face, making for excellent plugs for sealing optional knockout holes.

APM Hexseal’s self-sealing fasteners and sealing washers – When simply fastening just isn’t enough!

More Info


We are honored to serve as a manufacturer’s rep for APM Hexseal. APM Hexseal has an extensive line of standard silicone sealing boots that mate with the vast majority of switches, breakers, encoders, potentiometers and many other rotating devices found today throughout the world.

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