The O'Neill Mutant boot 6/5/4 with internal split toe is one of the most popular ones in the range. The 6/5/4 stands for different thickness neoprene panels that offer extra warmth. The boot features a soft sole to retain that 'barefoot' feel on the board while the internal split toe helps with your balance on the board without losing heat as you might with an external split toe boot.  Who is it for:  A great choice for surfers, paddleboarders, windsurfers and kitesurfers who like a split toe without wanting to compromise warmth. Features: FluidFlex™ Firewall Internal Taped Seams Internal Split Toe Sealed GBS Ultralight Foxing Support System