Hellermanntyton alpa pa66 locknut hellermann tyton 166 50138 the hellermanntyton 166 50138 is a polyamide 66 pa66 locknut from the alpha range the locknut is supplied with a m40 metric thread this locknut has been designed to accompany the hg s series of conduit the locknut is supplied in black hellermanntyton 166 50138 alpa m40 alpa pa66 locknut