The bowflex 552 dumbbells:

This design combines the power of 30 separate dumbbells down to 2, which saves space and money. With just the turn of a dial you can automatically change your resistance from 5 lbs (2.27 kg) all the way up to 52.5 lbs (23.8 kg) of weight. With two bowflex selecttech 552 dumbbells you can achieve a complete full body workout.

Product details:

Weight range: 5 to 52.5 lbs (2.27 to 23.8 kg) each dumbbell

Maximum number of exercises available: 30+

Number of weight settings: 15

Weight settings: 5, 7.5, 10, 12.5, 15, 17.5, 20, 22.5, 25, 30, 35, 40, 45, 50, and 52.5 lbs.

Dimensions (dumbbells): 15.75" l x 8" w x 9" h (40 l x 20 w x 23 h cm) (each)

Dimensions (stand): 27.75" l x 20.5" w x 24.5" h (70.5 l x 52 w x 62.2 h (cm)

Weight: 52.5 lbs (23.8 kg) (each)