The Muscle Baller is brought to us from the inventors of the famous BackBaller, (Dual Mounted Foam Roller). Muscle Baller is the single more compact version, it provides the stable base in which we can perform all our favorite SMR techniques with incredible control & stability.. Features -. Single-Mounted Roller. Rollers are interchangeable. Compact Design – Ideal for your kit bag. Not recommended for rolling your Back – Rolling on a single roller tends to over arch your back.. Tested to take 300kg. EVA Foam Roller with Steel Bearings. Rubber Grips