Isurus took a new approach to pattern making for surf wetsuits. Since the 1950’s clothing patterns for shirts and coats have been made with the arms hanging at your side. Works great for street clothes, even running. For paddling, it is restrictive. Think what happens when you lift your arms overhead when wearing a coat.
Isurus designed the wetsuit patterns with the arms raised overhead so your arms are now in the optimal power position for paddling. Such an arm position minimizes resistance and gives you increased forward reach with more power and less shoulder strain.