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.
It should be a 7 mm Allen.
Most likely for this type of van is a 3/8 Allen wrench.
The front caliper on a 1995 Ram is requires a 3/8 inch Allen wrench to remove the bolts.
Depending on which model caliper it will be 7mm or 3/8 Allen.
7 mm
7mm.
I believe that is a 3/8 Allen.
3/8 inch Allen wrench
45t
19mm deep socket for wheelnuts, 7mm Allen wrench to remove caliper bolts, 8" c clamp to push piston back into caliper housing
7mm
7mm hex socket