3mm Hyper Flex AMP Split Toe Soft Sole Surf Booties Bootie These are AWESOME HyperFlex AMP 3mm Split Toe Boots from Henderson HyperFlex LOCKSEAL Anti-flush closure on the top of the boots form a water tight seal 100% SEALED SEAMS Glued, blind stitched and exterior liquid taped Dual-density construction. 3mm upper and 2mm footbed allows a thicker, warmer boot No more slipping side to side. You are locked in with the AMP boot