Rubber Hexagon Dumbbells are quite popular especially for Crossfit and Functional training.
Often people prefer round dumbbells as you can push dumbbells around with your feet. This is not the right way to transport dumbbells. Dumbbells should always be picked up and never rolled around or dropped.
Hexagon dumbbells are used like normal round dumbbells, but it does allows you also to do pushups with the hexagon dumbbells. The hexagon dumbbells will ensure that the dumbbells don’t move around during use.