O'Neills Hammer vest is a flexible lightweight rash vest which offers protection from UV and rashes.We wouldn't recommend wearing this type of vest under a wetsuit which already has a fluffy polypro lining it works perfectly on it's own when surfing in hot climates. Features Seamless Paddle Zones Boardshort Connector Flatlock construction U.P.F. 50+ Rash protection 100% Superstretch Size Guide The rash vests use the same size chart as the wetsuits please note not all sizes are available in every style. Size: Large,Medium,Small.