I needed a Hex 9MM worked great
To remove the front brake calipers from a 2008 Mercury Mariner, first, ensure the vehicle is on a stable surface and secure it with wheel chocks. Lift the front of the vehicle and remove the wheel to access the caliper. Next, use a socket wrench to remove the caliper mounting bolts, then carefully slide the caliper off the brake rotor. Support the caliper with a bungee cord or wire to avoid strain on the brake line while you work on the brake pads or rotor.
9mm hex socket bit
mercury mariner
Change wheel bearing on 2006 mercury mariner
The front caliper bolts on a 2008 Mercury Mariner typically use a size 13mm hex bolt. It's important to check the specific vehicle's service manual for exact specifications, as variations can occur based on production changes. Always ensure to use the correct torque specifications when reinstalling the caliper bolts.
On the inboard side of the caliper.
The easiest way is with a "C" clamp.
Each of the calipers is held in place by two bolts. Remove the bolts and then the caliper. If necessary you may need to retract the caliper piston using a screwdriver or large C-clamp.
It takes a T55 Torx bit on the front calipers.
Remove the front wheel. Loosen and remove the two 15 or 17 mm bolts securing the calipers in place (access from the back side of the calipers). Lift the calipers out of the way and your rotor will be somewhat loose. Pull off the rotor.
Your local parts store should be able to help / answer that question.