king kutter finish mower blade mounting bolt kit 502310 bap replacement blade mounting kit for king kutter rfm series finish mower. this listing is for three (3) 1/2" x 1-1/2" left hand thread bolts with concave blade mounting washers, a full set for your mower specifications: 1/2" diameter x 1-1/2" long left hand thread 1/2" concave spring washers that are 1.50" in diameter