Rotary 9031. RENEWS DAMAGED THREADS. REMOVES CARBON & CORROSION WITH A FEW TURNS. ALLOWS FIRM SEATING OF PLUGS. ASSURES METAL TO METAL CONTACT FOR EFFECTIVE HEAT TRANSFER. LONG HEX DESIGNED TO PREVENT WOBBLE. NEOPRENE RING HOLDS CHASER SNUGLY IN SOCKET. MADE OF