螺絲攻，3/8"-20螺紋，塞規型，左手

These plug taps cut through a 3/8" left-hand thread in stainless steel smoothly without any chatter. The 3-5 chamfered lead makes starting the thread straight and easy.

Finally got around to using this on some aluminum and the left-hand threads cut clean without any chatter, which surprised me given how stiff plug taps usually feel. The 3/8"-20 size lined up perfectly with my die holder, and the 3-5 chamfered teeth made starting the cut way less fiddly than I expec

Had to redo a stripped left-hand hole on a stainless bracket and this plug-style tap cut cleanly without grabbing, the 3/8"-20 threads came out sharp. Chamfer did its job clearing chips on the first pass, exactly what I needed for a quick fix.