The Cognito 110-90258 Shock Extender Kit for your 2011-2016 GM 2500HD/3500HD 2WD/4WD is designed for use with some stock and Cognito Upper Control Arms. See specific lift kit or control arms for application. Features: Shock Extender Kit Works With Cognito Shocks & UCA Kit Specific Applications Include: Leveling kit using stock shocks and stock upper control arms. Leveling kit using Cognito UCA kit with Cognito shocks. Cognito lift kit used with Cognito UCA kit and Cognito shocks.