its not a hex,,,it`s a torx t30 i believe
It takes a T55 Torx bit on the front calipers.
American cars never used Bristol keys. The Suburban most likely uses a 3/8 Allen key on calipers.
18 mm I think.
it takes a 7mm Allen wrench to remove calipers on 2003 ford focus.
3/8" Allen wrench
The T60 is the size needed to remove caliper bracket.
15 mm
I believe that will be a 7mm Allen key.
I needed a Hex 9MM worked great
A 3/8 inch Allen key is used.
7mm Allen wrench
You need to go to an Auto Parts Store and have them look it up. It's usually a special wrench used only for the brakes. Hope this helps.