The self-locking washers are acting a fixed function after the insulation install on the CD weld pins,Website:http://www.insulationpin.net, self-stick pins, perforated base pins, Lacing anchors, the self-locking washer hole size depend on the pin diameter to have a good hold powerMaterialLow carbon steel, Aluminum, Stainless steelPlatingGalvanized coating or cooper plating for low carbon steelNo Plating for Aluminum or stainless steelSizeSquare self-locking washer2.5"×2.5" 1.5"×1.5" 1.25"×1.125"Round self-locking washer1" 1.18" 1.5" 2"Use forPin diameter: 10GA( 3.4mm), 3mm, 12GA( 2.7mm) 14GA(2.0mm)