Star-Lock washers are a brand name of a push-on fastener manufactured for the purpose of gripping onto round shafts. Once pushed on to the shaft, they grip immediately. Once secured, Star-Lock washers are almost impossible to remove without damaging and probably destroying them.
They are commonly used on the axles of prams and pushchairs to prevent the wheels from working loose.
Capped Star-Lock washers feature a push-on cap that hides the internal serrated section of the washer.
An imperial washer can be used in conjunction with all types of non-metric threads including UNC, UNF, BSW, BSF, BA etc.