SmartCuffs 4.0 is the 4th generation model of the most popular blood flow restriction (BFR) product in the world. They are designed to be the most comfortable and evidenced-based cuffs for users of all types and can fit either your arm or leg. This 4.0 model, with its AI-powered processor and proprietary limb occlusion pressure (LOP) algorithms, makes it the most intelligent BFR cuff on the market today. Its patent-pending iBFR LOP Calibration can find LOP in as little as 10 seconds. By taking a percentage of LOP, the user can objectively know how much they are restricting blood flow for their given body structure. This is critical since LOP's vary wildly from person to person. Thus, taking out all the guessing for a truly easy and quick experience. The exclusive Tri-Pressure technology features three distinct BFR modes that have been shown to be highly effective. The Continuous BFR mode inflates the cuffs during exercise sets and rest sessions. This is ideal for advanced rehab or de-loading joints because your muscles will fatigue at a higher rate. The Intermittent BFR mode inflates the cuffs only during exercise sessions and will deflate during rest sessions. Ideal for beginner rehab or de-loading joints. The Resting BFR mode inflates the cuffs only during rest sessions and deflates during exercise sessions. Ideal for beginner rehab to ease into BFR training (using very light weight) or advanced rehab (using heavier weight). SmartCuffs 4.0 was designed to not allow the user to inflate to a percentage greater than 80% LOP for any limb. Making the 4.0 safe and easy to use for at-home patient use. The rechargeable Li-Ion battery has incredible battery life and can be fully charged in 30 mins or less. Each cuff has its own pump permanently affixed to it. These are a pair of sized medium cuffs, with each having a circumference of about 13 to 18 inches. If you want the cuff to fit your arm, measure the circumference of the space between your shoulder and bicep. If you want the cuff to fit your leg, measure the circumference of your thigh closest to your hip. If you are on the border, choose a larger size. Included with your pair of SmartCuffs is a carrying case, USB-C charging block and cable.