10-24 x 1/2 Unslot Ind Hexwasher Serrated Self Drilling Screw Full Thread Zinc Bake D6923188 and the 1/2 refers to

and the 1/2 refers to the length of the bolt

The 1/4-20 x 1/4 Slotted Pan Machine Screw Fully Threaded Zinc is a versatile fastener designed for various applications

This 1/4-20 x 1 1/2 Phillips oval head machine screw is fully threaded and has a black oxide finish

The fender washer is ideal for use in automotive

and the pan head provides a low profile and a wide bearing surface

10-24 x 1/2 Unslot Ind Hexwasher Serrated Self Drilling Screw Full Thread Zinc Bake D6923188 and the 1/2 refers to10 24 x 1 2" Unslotted Hex Washer Serrated Self Drilling Screw, Full Thread, Zinc Plated This screw is designed for use in metal applications. It has a hex washer head with a serrated flange that digs into the metal, creating a secure hold. The self drilling tip eliminates the need for pre drilling, making installation quick and easy. The full thread design provides maximum holding power. The zinc plating provides corrosion resistance.