Various Gm Models See Amazon Chart / Liftgate, Tailgate, Prop / Lift Supports, Struts. Units Are Pair (2) Priced L & R 4557 This item is sold as (2) units 1 matched pair 4557 StrongArm Strong Arm Extended length 24.69" (measured center to center of ball studs or eyelet ends) Compressed length 15.69" (measured center to center of ball studs or eyelet ends) Easy to install, most vehicles using a small flat headed screw driver.