Need a little help for ring set, I need wiseco rings bored .5mm over (64.50mm). I've down loaded the adobe version, but there is 3 different types as far as material. 1. alloy steel, ferrox coated, chrome faced, internally notched 2. alloy steel, ferrox coated, titanium nitride faced, internally notched 3. alloy steel, ferrox coated, chrome faced, internally notched <== this seems the same as 1 but have them listed sereratly. Little help please?