Billabong Foil 5/4/3 GBS Back Zip Full Wetsuit: Keeping you warm while the waves temp your adventurous side, The Billabong Foil 5/4/3 GBS Back Zip Full Wetsuit is suited for action. Featuring Zero Gravity Superflex, a modular hood, knee pads and ergonomic performance paneling, the Billabong Foil 5/4/3 GBS Back Zip Full Wetsuit knows how to hit a wave.