motion of the board will challenge and engage every leg muscle, giving you more definition while burning calories. Strengthens hamstrings, quads, glutes, and calves. This ultra-efficient, low-impact workout will improve your overall fitness, agility, and core strength. The non-slip surface and solid pivot point make it an appropriate fitness tool for beginners to advanced participants. Get two and use for shadow boxing and enhanced balance drills. Size: 14" Diameter.