The NEW TwistLock Dumbbells are the most space efficient and easy to use home dumbbell system available on the market today. The patented cutting-edge technology allows weight adjustments with the simple twist of the dumbbell handle. You never have to take your hands off the dumbbells - no knobs to turn, pins to align or levers to slide. You simply place each dumbbell into the cradle and twist the handle to your desired weight selection. Twist and Go!