Here's what ZemGear has to say:
A leader in the minimal footwear industry, ZEMgear creates Performance Protection for Bare Feet. We deliver minimal footwear with maximum protection to men, women and children. ZEMs allow your feet to do what they were designed to do best in their natural, barefoot state: While wearing ZEMs you can spread, flex and articulate all parts of your foot – getting everything you need and nothing you don’t. Our 4-way stretch Lycra uppers & soft molded rubber bottoms allow the foot to move with complete freedom. Six unique high-frequency tech bands are welded across the top of the foot to keep the ZEMs securely in place around the foot.