High Collar Lock Washers - Grade 8 Yellow Zinc High Profile Split Ring Lock Washers Designed to fit under the head of a socket cap screwAdds resistance when tightened to prevent rotation while vibratingGrade 8 high collar split rings offer corrosion resistance and strengthApplicable Standards: ASME B18.21.1, DIN 127B, NASM 35338(formerly MS 35338 and AN-935) High Collar lock washers are designed to fit under the head of a socket cap screw. A split washer or a spring lock washer is a ring split at one point and bent into a helical shape. This causes the washer to exert a spring force between the fastener's head and the substrate. The exerted force helps adds resistance to the nut or bolt making it harder to loosen. High Collar lock washers are primarily used where fasteners are likely to vibrate. Sizing Specifications: "OD" = Outside Diameter, "THK" = Thickness 1/4" : 0.363 OD, 0.078" THK3/8" : 0.550 OD, 0.125" THK7/16" : 0.644 OD, 0.140" THK1/2" : 0.733 OD, 0.172" THK5/8" : 0.917 OD, 0.203" THK3/4" : 1.105" OD, 0.218" THK7/8" : 1.291" OD, 0.234" THK1" : 1.478" OD, 0.250" THK High Collar Lock Washers - Grade 8 Yellow Zinc Grade 8 Yellow Zinc Lock Washers, also known as Split Ring Lock Washers, Locking Washers or Spring Lock Washers, in this selection are made of yellow zinc plated Grade 8 steel. Grade 8 steel is valued for its hardness and durability, and the yellow zinc plating adds corrosion resistance and even more durability. Split Ring The split ring style is perhaps the most common style of lock washer. The helical shape of the washer exerts force between the fastener and the installation surface, resulting in a bolt or nut that becomes resistant to loosening due to vibration. Additionally, the edges of the split may add additional resistance to movement by digging into the fastener and the installation surface. High Collar - Small OD High Collar Lock Washers have a smaller outer diameter than a standard lock washer, and are designed to be used with socket cap screws. The high profile and smaller outside diameter of these lock washers make them ideal for counter-bored holes, or any application where there are space limitations.