Made to strict standards of flatness and accuracy, our steel washers make ideal contact points for magnetic fastening systems. The three smaller sizes are 3/32" thick and have a 1/8" dia. hole countersunk for a #4 screw, while the two larger sizes are 5/32" thick and countersunk for a #10 screw. The outside diameters are slightly undersize and match their respective cup, so that the same size of drill bit can be used for counterboring both when you want them flush mounted. Can be installed with machine screws for improved pull-out strength. Sold individually. Made in Canada.