Here is a MMA grappling dummy that helps you work on your ground & pound, submission, and tackling. The Knockout Fightgear Ground & Pound Training Dummy is available in 50lbs and 25lbs versions. It has reinforced handles for throws, thrusts, and all kinds of other moves.
This BJJ dummy features triple-lock stitching. It measures 30″ long. You can find out more about it here.