AO/J Plus: Blue Fired Aluminum oxide, J-Flex 100% Cotton, 60-400 grit: A highly flexible product with a grinding aid for use on most metals and hardwoods. Easy to tear. Great on stainless steel, brass & other alloyed materials (very popular with Knife makers for both blades and handles). Our most popular J-Flex belt. Primarily used for narrow belts, dry only.