self drilling trailer deck screws

The incorporated washer, on the other hand, serves multiple purposes. Primarily, it increases the bearing surface, thereby distributing the load from the screw more evenly across the material it's screwed into. This prevents damage to the surface, such as splitting or indentation, which can occur when a screw is tightened without a washer. Additionally, the washer can also help in reducing friction and preventing loosening due to vibration.

...

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.

...