In the past few years, we have covered plenty of adjustable dumbbells here. The BowFlex SelectTech 840 Kettlebell is also worth a look. It can replace 6 kettlebells. Its weight can be adjusted from 8 to 40lbs. It has a space saving design but still lets you perform swings, rows, squats, and other moves.
This kettlebell has a convenient weight selection dial.