The Rollerblade Maxxum Edge Middle Buckles match those from the Maxxum Edge Skates, but use standard (SMB) mounting to be compatible across many brands and models using the same common mounting method.  Also referred to as ankle buckles, powerstraps, or 45-degree straps.
 
Standard Middle Buckles (SMB). Two-point mount buckles or straps that mount at one point on each side.  SMB buckles and straps are compatible across different brands and models using this same mounting method.