... Fully re-inforced premium quality suitable for all metal cut off wheelsFully re-inforced premium quality, general purpose metal cutting discs ... ': 1) t41: t41 flat cut off discs 2) a30: oxide materials grit 30 3) r: harness grade 4) 8: structure no. 5 ... applications of discs: 1) characteristics: standard quality, made of normal grade corundum ( oxide) , medium hard bond, flat type black color, high ...