This is top of the line Shock made from reputable FASTACE, not those $30 mickey mouse shocks others selling.   FASTACE 280MM RACE SHOCK - Air/Oil/Coil Spring (1000 lbs/IN) CONDITION: Brand New MODEL#: BDA-51AR/BS-58AR Measures 11"(280mm) eye to eye. Light weight, ergonomic, adjustable rebound, easy turn adjustable spring pre-load, nitrogen-charged, externally adjustable rebound damping!! This shock is ideal for bikes that have the stock style extended swing arms. The shock will double your travel and raise your seat height above 2". This is a quality rear shock and comes with AL6061 T6 forged shock body, easy-turn spring preload nut, oil damping with floating piston, preload and rebound adjustment. Upgrade for stock and replacement for SDG and other pit bikes, it is ideal for bikes that have the stock style extended swing arms. Recommended for serious riders only Mode  Material  Surface Weight Length Stroke BS-58AR AL6061 T6 forged aluminum body Dark hard anodized 1135g 280mm 70mm Adjustable Rebound switch F (fast) and S (slow) at the bottom of the shock *** shocks are non -returnable, while it fits most CRF/xr 50 style bikes, some year model may not fit without modification, please make sure this is the one you want by checking with your local dealer