Those are the weights of the pistons in grams so one is 1 tenth of a gram heavier - not a big deal.m.aurelius said:I was told that they are more light weight. But then again might be BS. oh yeah there are marker writings on the bottom of each piston. 3 pistons say 283.1 and one says 283.2. Is this normal? Oh yeah, they said they had them coated.