This is a st")andard Clamp Style stainless steel coil strap, it comes with everything you see in the picture.
 
  This is for a pair
 
Coil fin strap

Rust resistant stainless steel spring straps are ideal for technical and recreational diving applications. The main advatage is fins become easy to put on or take off when fitted. Each style has 4 lengths for comfortable and secure fitting .

Approximate spring length

S: 17.1cm (6 3/4")
M: 19cm (7 1/2")
L: 21cm (8 1/4")
XL: 22.8cm (9")