Nylon Insert Lock Nut - M4 x 0.7 - Steel - Zinc CR+3 - UNC - Class 8 - DIN 985 - 100 Pk - BBI 812010

Nylon lock nuts contain a nylon collar insert to help prevent turning. the insert deforms elastically over screw threads. the nylon insert applies a compressive force against the screw to lock the nut.