car seat cushion
poly-foam padded cushion can be swivelsed and it is portable

car seat cushion
This portable, poly-foam padded cushion swivels 360-degrees in any direction alleviating the strain on back and hips. This swivel cushion helps you get up from any seated position, especially helpful with getting in and out of vehicles. The swivel cushion weighs only 3 ¼ lbs. and measures 15 5/8" in diameter. This portable cushion supports up to 800 lbs. and is available in a gray, velour cover or a fleece cover. Covers for this handy cushion are removable and washable.