IMPROVE YOUR PUNCHING SPEED, POWER, AND ENDURANCE.BURN MORE CALORIES AND INCREASE YOUR CARDIO. Secure Grip: KNUX are ergonomically molded to fit your hand resulting in a comfortable and secure grip. More Effective: The weight of the KNUX is centered at the front of your fist to mimic the weight of boxing gloves and optimize the effectiveness of your workouts. Versatile: Designed for shadow boxing and HIIT workouts but work great for walking, running, and stepping aerobic workouts. Sizes: Available in 1lb, 2lb and 3lbs, you’re sure to find a weight to help meet your fitness goals.