Back Loop Custom Strap Kit. For those that need something extra, the "Back Loop" custom strap kit provides another level of security. In addition to the regular strap, the back-loop kit has an extra long leather strap which attaches to the back of the upper at the heel, and loops around the high ankle area. It's purpose is to help keep the heel in place from slipping up and down, thereby giving the dancer more control. Advantages: -Support at the upper ankle area -Helps reduce ankle sprains -Helps minimize slipping up and down the back of the heel RUCUSTSTRAP$12.00Size: Small 9sm-1Medium 1.5-4.5Large 5-8.5 Awarded Yahoo 5 star top service rating by Yahoo Shopping, and Shopping.com shoppers.