The Universal Heel Brake (UBS) - by Powerslide. A useful brake for many skates on the market made from glass-fibre reinforced plastic. A unique feature is that the brake's width is adjustable to sit on wider frames and is compatible with up to 4 x 100mm wheel configurations. 

Compatibility
Fits wheel configurations up to 4 x 100mm
Works with FR Skates FR1 80 and FR1 80 Deluxe model
Doesn't work with rockerable frames