ULTRA-LIGHTWEIGHT BAREFOOT TRAINER :The updated Primus III has the same ultra-lightweight design and flexible, grippy sole of our bestselling barefoot kids' trainer, made using recycled, animal-free materials NEW TONGUE CONSTRUCTION: Now engineered with a new tongue construction for a wider opening, letting kids pull these everyday sneakers on and off by themselves TOGGLE FASTENING: for a snug, sporty fit that keeps out the its", but lets all the feeling in, making sure feet grip, balance and flex as close to barefoot as possible." Strong Feet For Strong-Willed Kids. The Primus Iii Is An Ultra-Lightweight Barefoot Trainer For Preschoolers. Now Extra Easy To Pull On And Off.