Kettlebells are wonderful for strength training. The Bowflex 840 SelectTech Kettlebell can replace multiple kettlebells. You can change the resistance from 8lbs to 40lbs with the turn of a dial. In fact, you get 8, 12, 20, 25, 35 and 40 lbs weight options.
You can do swings, rows, squats, twists, and a whole lot more moves with this adjustable kettlebell.