6-32 x 5/16 Six Lobe Pan Thread Cutting Screw Type F Fully Threaded Zinc NHHSP and the 4 1/2 refers

and the 4 1/2 refers to the length of the bolt

The 5/16-18 x 1 1/4 Serrated Hex Flanged Washer Full Thrd Grade 5 w/Head Markings Zinc Yellow is a type of washer that is used to distribute the load of a bolt or screw over a larger area

and the threads on the bolt engage with the metal or wood

This 10-32 x 3/4 slotted oval machine screw is fully threaded and made of zinc

5 x 10 ISO7380 Metric 6-Lobe Button Head Cap Screw Class 10

6-32 x 5/16 Six Lobe Pan Thread Cutting Screw Type F Fully Threaded Zinc NHHSP and the 4 1/2 refersThe 6 32 x 5 16 Six Lobe Pan Thread Cutting Screw Type F Fully Threaded Zinc is a small, versatile screw that is commonly used in a variety of applications. It is made of zinc plated steel, which gives it good corrosion resistance. The screw has a six lobe pan head, which provides a large bearing surface for driving and prevents cam out. The thread cutting design allows the screw to create its own threads as it is driven into a material, making it