Here is another kettlebell handle that lets you do more with your dumbbells. The Grip N Rip Fitness Adjustable Dumbbell to Kettlebell Converter can handle up to 75lb of load. It has a locking mechanism to properly secure your weight. It is made of PA6 to withstand your workouts.
This kettlebell handle works on any dumbbell with a diameter between 1 to 1.5″. You can find out more about it here.