This buckle is 18cm long.
The set includes both left and right.
This is the buckle that sits on the top of your skates and is mounted on the cuff.
They always have 2 mounting bolts (15mm apart) on the outside of the skate, and one mounting bolt on the inside of the skate for the buckle receptor. That means in total there are 3 holes. Buckles that are mounted like this are called SBM3 which stands for Standard Buckle Mount with a total of 3 bolts
Top buckles can vary in length but are also easy to cut to the right size.