This is the Tilos 5mm Titanium TruFit Thermowall Booties for Scuba Diving BootFeatures: Lower Volume: TruFit boots have less volume over the instep. This reduces excess water in the boots which makes them warmer. It also makes it easier to get in and out of your fins. Trufit Sole: Comes with built in arch support and a heel cup. The arch keeps the foot in a natural position which applies more power to your kicks and comfort when you're on land. The heel cup supports natural padding in your heel to absorb shock when walking. Asymmetrical Toe Box: The toe box on TruFit boots is shaped like the outline of your toes. This reduces dead space around the toes for a perfect fit. Rocker Sole: The rocker shape of the sole allows you to "roll" through your step in a more natural way. This reduces fatigue and improves balance. Metal YYK Zipper: All Tilos TruFit boots come with high quality metal zippers that stay put. No need for zipper keepers here! 5mm lined with Thermowall lining enhance heat retention & quick-dry feature 8" (20.3cm) lengthened height for extra warmth & protection Punch proof sole Internal double smooth-skin seal flap at zipper reduces water entry Built in strap stopper Flexible vulcanized sole Double glued and blindstitched so you won't feel the seams inside the boot. "