Made by Grip & Lift Australia in AustraliaThe Wrist Roller is made of Stainless Steel, 52mm in diameter.  The thickness of the unit makes you work harder.  5 feet of high quality rope and a stainless steel heavy duty carabiner.Hold arms straight out front shoulder width apart and roll the Wrist Roller until the weight has reached the top.  And then slowly let the weight down until it hits the end of the rope.  Start with light weight. Great pump and intense training for your forearms.