O\'Neill Mutant 6/5/4/mm Internal Split-Toe Wetsuit Boot in Black The O\'Neill Mutant 6/5/4/mm Internal Split Toe Wetsuit Boot is a cold water neoprene boot designed for the coldest UK conditions. A performance boot that has been upgraded with improved fit and durability. The interior Firewall Neoprene provides the warmth and the split toe gives you that extra little feel in your feet. A boot that has it all - comfort, flexibility and performance! Features    Multidensity Rubber Sole for Max Feel 100% Sealed Big toe separated for balance and dexterity Exterior: FluidFlex Heel Pull Tab Interior: Firewall Sealed Glued andBlindtitched Seams New SuperSeal Closure - seals water out while providing plenty of opening Forefoot Foxing Support System (Strap-free)