The GiroDisc titanium pad shield for StopTech ST40 calipers is a replacement shield matched to that caliper model. It installs behind the pad to help protect surrounding components from heat and debris and is specified for front or rear fitment where StopTech ST40 calipers are used, per the description. This shield is provided to match that caliper's hardware layout.
GiroDisc StopTech ST40 Caliper Titanium Pad Shields