One New Aftermarket Replacement Pack Of 25 Left Hand Disc Mower Blades That Fits New Idea Disc Mower Models: 5209, 5212 (Both SN 16013 Up), 5406, 5407, 5408, 5409, 5410 (All SN 1007482 Up), 5312. Fits Challenger Disc Mower Models: Htd7, Htd7B, Htd8, Htd8B, Htd9, Htd9B, Ptd9. Fits Hesston Disc Mower Models: 1004, 1005, 1006, 1007, 1008 (All SN 1010846 Up). Fits Massey Ferguson Disc Mower Models: 1306, 1307, 1308, 1309, 1310, 1326, 1327, 1328, 1329, 1330.