double threaded rod

A Tek screw, also known as a self-tapping screw, is a specialized type of screw designed with a sharp point and thread that cuts into the material it's screwed into, eliminating the need for pre-drilling. The 4-inch variant is particularly popular due to its versatile length and load-bearing capacity. It strikes a balance between being long enough to provide substantial hold in thicker materials while remaining compact enough for use in various projects.

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Metal expansion nuts, often referred to as expansion anchors or expansion inserts, are specialized fasteners that expand when a bolt or screw is threaded into them. They typically consist of a cylindrical body with slits along its length or an expandable design that facilitates outward expansion. The main purpose of these nuts is to create a secure grip within a substrate, such as concrete, wood, or metal, thereby preventing loosening due to vibrational forces, temperature fluctuations, or stress.


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