 I.e.using a 167 mm long magazine tube with a 3 mm basepad would yield an overall length of 170 mm making its configuration approved for international competition, while a 167 mm magazine tube with a 4 mm basepad would yield an overall length of 171 mm making it restricted to USPSA matches only.Adding to the confusion, some manufacturers lists their magazine tube length as the length of the tube itself, while others lists the length with a basepad assembled.