Replaces part numbers 5321687-10, 5321687-21, 5321804-24, 5321804-25. COMPLETE HARDENED STEEL BLADE SET. ONLY AVAILABLE FROM ISE FOREST AND GARDEN. Full Set of Blades for a 42 Rear Discharge Deck Hole: 5/6 Star & 10mm Length: 543mm. FULL SET OF CROSS BLADES. 1 X 5 STAR CENTER, 1 X 6 STAR CENTER AND 2 X CROSS SECTION BLADES LEFT AND RIGHT. FIT ALL HUSQVARNA, MCCULLOCH, JONSERED AND CRAFTSMAN AYP MANUFACTURED 42 INCH MACHINES WHICH TAKE 4 X CROSS BLADE SET.