This is a high quality billet axle spacer kit to replace the plastic Ski-doo oem axle wheel spacers found on most 2008+ xp,xs,xm chassis sleds. This is the piece that typically is cracked by your track adjuster bolts and then causes a crooked axle and then broken parts throughout the rear axle. Put these on now and eliminate one more little piece that can easily end a good trip. Sold per pair. IF YOU ARE DOING A 4 WHEEL AXLE KIT YOU NEED 2 SETS (4 BLOCKS) TO REPLACE ALL THE FACTORY PLASTIC BLOCKS!