The Concorde Gilding Discs are Double sided for versatility and work on both carpet and hard floors. The smooth side are for carpeted areas and the fabric side are for hard floors. From lunges and squats to upper-body exercises, users can target specific muscle groups and tone their entire body with easy use. These workout sliding discs come in a 7" diameter to accommodate almost any user. Plus, with virtually every move, users can engage their core, giving them a strong abdominal work out.