I believe that's a 3/8 allen wrench, but it's a really simple matter to get under the vehicle and try different wrenches on until you find the correct one. Many calipers are held on with a 3/8 allen bolt, but some are 10mm and some even 1/2 regular bolt.
Depending where it was built, a 3/8 Allen key or 15 mm regular wrench.
The front caliper on a 1995 Ram is requires a 3/8 inch Allen wrench to remove the bolts.
7mm Allen wrench
I believe that is a 3/8 Allen.
Allen wrenches come in various sizes. There is no definitive information as to what size is needed to remove a brake caliber so you will need to match the wrench size to the best of your ability.
3/8 inch Allen wrench
The last one of those I worked on was 3/8 Allen key
Remove the two bolts and use a screwdriver against the hub and caliper.
With a wrench!!
A 3/8 Allen key.
3/8 in.
Remove wheelsRemove caliper mounting boltsSilide caliper off rotorRotor should slide of hub assembly