The Bowflex SelectTech 840 Adjustable Kettlebell eliminates the need for six individual kettlebells by packing weights from 8 to 40 pounds into a single space-efficient unit. The dial adjustment system lets you select your target weight in seconds by rotating the numbered dial at the base, then lifting the handle — the selected weight plates engage automatically. This is particularly valuable for circuit training where weight changes between exercises are frequent. The six weight settings (8, 12, 20, 25, 35, 40 lbs) cover the full progression curve for most users, from learning fundamental movements at 8 pounds to challenging swings and presses at 40 pounds. The compact storage footprint — essentially the space of one kettlebell — makes it ideal for home gyms with limited storage. While adjustable kettlebells are bulkier than fixed-weight bells and not suitable for some advanced movements, they are the most space-efficient kettlebell solution for home use.