FX Sport VRX Waterproof Silicone Skin plus Swimcap. The silicone skin swimming accessory is a flexible silicone case, into which the FX-Sport VRX headphones (supplied seperately) are inserted, to make the headphones fully waterproof for swimming. They also come with a stylish black FX-Sport nylon/spandex swim cap, which is a little larger than average to accommodate the accessory at the back of the head. And get this FX Sport VRX Waterproof Silicone Skin plus Swimcap Now £19.00.