Halcyon's Spring Heels fulfill a common desire for a fin straps that is flexible, yet remains secure and resistant to breaking. By eliminating all the failures common to convoluted plastic connections, divers are freed from the risk and hassle of lost fins and broken straps. Designed to fit Jetfin-style rubber fins. Automatically adjust to the diver's feet Compensates for depth and compression of boot material Unbreakable strap provides an amazing degree of comfort and peace of mind Stainless steel main spring and safety cable