The Heavy Handle Plate Kit has been developed to increase the weight range of our adjustable dumbbells. 2 piece plates fit on the inside of the handles against the backing plates. Still enough room for handgrip and is perfectly balanced. Most people rarely use less than 20 lb dumbbells so having a higher weight range that starts at 20 lbs is ideal. Now your 5-75 lb dumbbells can become 20-90 lbs! Or a 5-45 lbs set can become 20-60 lbs. Or you can even use this to add even more weight to dumbbells and the add on kit. 5-120 lb set can become 20-135!