MYFIT Powerdisc 45 - Upgrade your ride! The MYFIT Powerdisc 45 strap is an advanced heel lock system featuring a powerful disc closure system made by ATOP. It´s made for inline skates and roller skates which do not provide enough heel lock. Simply place the Powerdisc around your boot and tighten the strap well in order to lock your foot down. Recommended for: inline skates and roller skates which don´t feature a 45° closure system.