TheraBand Stability Trainers are oval-shaped, colour-coded pads. The green (firm) and blue (soft) TheraBand Stability Trainers are closed cell foam pads with an anti-slip ridged surface and oval foot fitting shape. The black TheraBand Stability Trainer provides advanced challenge. Made of durable PVC, the extra soft Stability Trainer's heavy gauge side walls resist the tendency to roll the ankle during exercise.