Black Tire Changer Machine Duck Head 30mm.1 This is a plastic mount and demount head with mounting bracket used on many tire changer machines. 2 Construction with high strength nylon and plastic material, quality and performance guaranteed. 3 Using plastic mount heads is much safer for delicate and expensive wheels yet durable enough to withstand the stress of larger tires and wheels. 4 Prevent damaging wheels from scratching damaging when clamping wheels from inside clamps. 5 Smooth surface, reduces friction, it is very easy to use.