M2.5 M3 M4 M5 M6 M8 Nyloc Nylon Insert Nuts A2 Stainless Steel Type T DIN 985
Nyloc nuts feature a nylon collar in the top portion of the nut that locks the nut in place by squeezing the threads of the bolt as the nut is tightened. This friction that is created prevents the nut from loosening.