Check the listing for details. OS 40-55 AX,FX,FSR,SF Standard RC Bearings. Condition: New. Listed at 4.97 USD. Picture is for bearing type only Picture is for engine type only OS 40 AXFXFSRSF Standard RC Bearings Front Bearing: R6-2RS 3/8 X 7/8 X .281 Bearing Rear Bearing: 6902M 15 X 28 X 7 Bearing with metallic retainer RCBearings two stroke rc engine bearings offer dependable, long lasting smoothness. These have as good or better performance than what came standard in your engine at a fraction of the cost of OEM bearings! NOTE: All heli engines .40ci and above should use a rear bearing with a high speed plastic retainer! Beware of other sellers that try to pass off cheap standard bearings with metallic retainers for your expensive heli engine! Support Email if you don't know which bearings you need or if you are looking for a kit we don't already have.