180 (inner length 17.0cm is equivalent to 25-26 yards)

190 (inner length 18.0cm is equivalent to 27-28 yards)

200 (inner length 19.0cm is equivalent to 29-30 yards)

210 (inner length 20.0cm is equivalent to 31-32 yards)

220 (inner length 21.0cm is equivalent to 33-34 yards)

230 (inner length 22.0cm is equivalent to 35-36 yards)

240 (inside length 230 equivalent to 37-38 yards)