A complete set of OE equivalent pistons and seals for the rear 2 pot Brembo STI caliper for Impreza WRX STI 2001-2018.
Comes with all items shown in the image, which includes 4 pistons and associated seals and rings and bleed screws. Covers both rear calipers.
2001-2018 Subaru Impreza WRX STI Rear 2 Pot Brembo Calipers
Should be installed by a qualified vehicle technician