Black Iron Strength® Adjustable Dumbbells Poles Apart® provides the convenience of 40 pairs of commercial use dumbbells in a compact space, however, not compromising on quality. Unlike other adjustable dumbbells on the market, Black Iron Strength Adjustable Dumbbells are the only commercial grade adjustable dumbbells. This system gives the user 40 pairs of commercial dumbbells in 12 sq. ft., making this unit space efficient. It an ideal system for the serious lifter. That is why these units are found in commercial and athletic facilities throughout the world as well as home gyms.