The XiKar Xi3 STS & STK have been coated with a high performance coating called Titanium Nitride, which now protects and stylizes the cutter. Used for many purposes, from aerospace equipment to jewelry, Titanium Nitride is a coating that creates an extremely durable exterior to the all stainless cutter. XIKAR's use of Titanium Nitride has created the multi-color eye-catching STS or the more subdued and sleek STK. Xi cutter blades are made of high quality 440 stainless steel with an HRC of 57. All Xi3 cutters features the same unique, ergonomic teardrop shape and double-guillotine action that gives the Xi and the Xi2 such powerful cutting ability in one simple squeezing motion. All Xi cutters are the same ring gauge: they will cut a 54 ring gauge cigar in half. Depending on how much cap you cut, they will cut up to a 58 ring gauge cigar.