Aventure Verticale British Arphidia
Very comfortable light to medium - weight one piece undersuit in fast draining, and very stretchy, comfortable material; lighter than, but similar to Powerstretch in look and feel. Generally they are meant to be worn close for maximum warmth. The flexibility is an advantage both for general ease of caving, and for reducing exertion (you're not fighting your clothing when you move). Also the close fit reducing chilling through allowing cold air into the system, while the relatively low bulk of the material facilitates fast draining.
These models (made especially by AV for us) for British caving, now have a shorter crotch-to-neck closure, which allows for a thicker and more heavy duty zip to be used. Double material pocket on knees, and a high collar for general snugness. It is easy to fit extra padding into the double fabric on the knees; an excellent feature which may help prolong a caver's career! Navy blue, sizes XS - XXL - remember, sizes are generally small and there is initial shrinkage on washing, although the material is very flexible.