Kneeboarding is a discipline of surfing where the rider paddles on his or her belly into a wave on a kneeboard, then rides the wave face typically on both knees. The typical kneeboard is between five and six and a half feet in length, with a wide round nose and constructed of Glassfibre over a polyurethane foam core. Kneeboard designers however are known for their wild experimental excess and so most modern materials including various aerospace elements such as Titanium alloys (for fins), carbon fibre and kevlar in epoxy matrices are not unusual. Modern kneeboards may have a rubber pad for the rider's knees, preventing undue wear of the knees, also preventing slipping to help the rider maintain control. Kneeboarders also typically use swimfins and an ankle surfleash.