The throat size is determined by the wall thickness.
Common wall compositions and their throat size:
2-1/2” metal stud, 1 layer of 5/8” sheetrock both sides: 3-3/4”
3-5/8” metal stud, 1 layer of 5/8” sheetrock both sides: 4-7/8”
3-5/8” metal stud, 2 layers of 5/8” sheetrock both sides: 6-1/8”
6” metal stud, 1 layer of 5/8” sheetrock both sides: 7-1/4”
8” block: 7-3/4″