Hellermanntyton alpa pa66 locknut hellermann tyton 166 50135 the hellermanntyton 166 50135 is a polyamide 66 pa66 locknut from the alpha range the locknut is supplied with a m20 metric thread this locknut has been designed to accompany the hg s series of conduit the locknut is supplied in black hellermanntyton 166 50135 alpa m20 alpa pa66 locknut