The 600 PRO-RMK 155 snowmobile is part of the lightest, strongest, most flickable family of sleds on the market - the PRO-RMK. The 600 engine is perfect for riders that want a high performance sled with instant acceleration. Instantaneous Lift Patented Raised AXYS® RMK® Chassis: The AXYS® RMK® features a patented, raised chassis that increases clearance and reduces drag to keep you on top of the snow. The AXYS RMK chassis, purpose built for mountain riding, allows for improved sidehilling, faster and easier climbing, and instantaneous lift allowing the sled to pop onto the snow faster. The aluminum overstructure is lightweight and durable for all types of riding. Taller spindles increases clearance to reduce drag. Rear Suspension: The lightweight, rigid rear suspension design features revised geometry to control pitch. This improves weight transfer, delivering better control and a more compliant ride. The rigid suspension delivers power directly to the snow. Off-trail, riders will notice improved weight transfer while maintaining the approach angle. On-Trail, riders will notice a more compliant and comfortable ride. The rear suspension features a rail design that helps lift the rear skid while driving it forward. 600 Cleanfire® Engine: This liquid-cooled Cleanfire® engine with semi-direct injection (SDI) deliver outstanding throttle response and instant acceleration. These powerful, efficient engines start easily and reliably and they calibrate automatically as the temperature and elevation change. These engines deliver impressive fuel economy in real-world riding situations, which, for Polaris riders, means aggressive, up-tempo riding, not low-rev lab conditions. In the AXYS® chassis, the 600 engine features lightweight integrated mounts, electronic oil pump and bypass thermostat. Electronic Oil Pump: Electronic oil pump eliminates power-robbing gear drive – and provides more precise, improved oil delivery for performance and durability as well as a 35% reduction in throttle effort. Requires no adjustments.