6 1/2 ------------ 21.25 to 21.375 ''
6 5/8 ------------------21.375 to 21.50 ''
6 3/4 --------------- 21.50 to 21.625 ''
6 7/8 -----------------21.625 to 21.75 ''
7 ------------------------21.75 to 22.125 ''
7 1/8 -------------------22.125 to 22.50 ''
7 1/4 ------------------22.50 to 22.875''
7 3/8 --------------------22.875 to 23.25 ''
7 1/2 ------------------23 .25 to 23.625 ''
7 5/8 ------------------23.625 to 24''
7 3/4 -------------------24 to 24.375''
7 7/78 -------------------24.375 to 24.75 ''
8 ------------------------24.75 to 25.125 ''