uxcell M8 x 16mm x 1.4mm Nylon Flat Insulating Washers Gaskets Spacers Fastener for Faucet Pipe Water Hose Black 100PCS;

Used for motherboard to prevent electrical short from metal to metal contact.
Fit for mother board standoff to use screw.
Washers are normally used to distribute loads of threaded bolts, screws, nuts, and evenly as the fastener is tightened.
Intended for the general use under the head of a bolt or nut in order to provide a smooth-bearing surface.