What Our Gearhead(R) Experts Are Saying:"These boots are a winter surf essential for me. The split-toe keeps my footing solid, and the TechnoButter lining adds serious warmth without the bulk. They seal well, stay snug, and hold up session after session in frigid water."When we're chasing winter swells in cold water breaks, the O'Neill Psycho Tech 5mm ST Boot keeps our feet warm, locked in, and protected from rocky entries and long paddle-outs. These boots are built to handle extreme surf conditions with an anatomical fit, durable outsole, and a split-toe design that improves balance and board feel. O'Neill's signature TechnoButter 3 neoprene and Firewall lining deliver insulation without weight, while the exterior Fluid Seam Welds block water entry. The addition of TB3X taped seams on the inside adds durability and comfort, and a sturdy instep strap locks in support through powerful turns. From Santa Cruz to the PNW, these boots are designed to perform in cold, demanding conditions.