Kuangmi Multifunctional Hand and Forearm Trainer Gripper Exerciser Strengtheners Benefit - Help you build lean,defined lower arms,strength the wrist,arm,and shoulder power,develop strong flexor muscles and larger extensor muscles,hand grip will work more muscles,reduces strain on joints Ergonomic product design - Soft grip shoulder,density foam cover to make you feel more comfortable when used Easily Portable - Accessory to complement the gym home training system,encourages more natural arm and shoulder movement that traditional push ups Lightweight & Easy to carry - Design with steel spring resistance,which is suitable for home,office,gym,exercise to use Material & Color & Model - Case material:ABS,Holder Materials:NBR,foam,Color:Blue,Red,Model(Torsion):5kg,10kg,15kg,20kg,30kg