Jointed Rubber Mouth Pelham Bit (by Smith-Worthington)Jointed Mouth Pelham with short cheek. Mouth thickness 21 mm. SW Bits are made of the world's finest 18 8 (chromium nickel) stainless steel. This alloy is best for bits because it extremely strong and resists salt and acids in saliva, and will never rust or spot. Our bits are investment (lost wax) cast from carefully crafted models of tested bit designs to insure consistently perfect quality bit after bit. Even with these advanced production methods,