This attaches to the back pin of the Heel Bracket assembly. It rotates up under the Heel Lever and prevents the Heel Lever on the back foot from pre-releasing when landing hard in a tele stance. This a stronger, more durable 3rd generation design, which we have improved with the help of our tele tribe.
Here are instructions for replacing it.
One (1) Heel Lock. Compatible with both the BMF/R and the BMF/3.