Gillingham High Performance Heavy Duty Hand Gripper Variable knurl depth - aggressive on the palm side, less aggressive on the finger side. Virtually indestructible label on the handle ends give GHP grippers a unique look and make gripper identification a snap whether open or closed! "SmartMark" grooves on the handles indicate where to put the gripper in your palm and where to place your fingers. Move your fingers up the handle to make the gripper more challenging. Radius edges give GHP grippers a streamlined look and don't beat up your pinky like the industry standard chamfered end. High carbon content Oil Tempered springs are polished for appearance and lubricated with a high tech odorless, colorless synthetic lubricant.