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. There are also special sponge earplugs provided, which block water from entering the ear, but allow sound. The reason the headphones are inserted into a case rather than fully waterproofing the headphones themselves, is that put simply, that does not work as well. Waterproofing the device means a lower level of music quality. Waterproof speakers are a lot less responsive than normal speakers and have less access to air for bass. Air pressure issues can also degenerate sound or volume. Within the silicone case, the speakers can use the air inside the case and also do not have to be fully waterproof, so the bass is much better. In addition, the supplied sponge earplugs provide a space through which sound can travel. The VRX system then allows the user not only to listen to quality audio, but take advantage of all the extra training/coaching functionality available from the Workout Store. So buy this FX Sport VRX Waterproof Silicone Skin plus Swimcap Now £19.00.