We measure the TWISTER at both ends with a digital caliper. The size is usually based on the larger end, so our size stickers are meant to be more of a guide, not precise measurements.

SIZE 5 = 5.00mm thru 5.99mm

SIZE 6 = 6.00mm thru 6.99mm 

SIZE 7  = 7.00mm thru 7.99mm

SIZE 8  = 8.00mm thru 8.99mm

SIZE 9 = 9.00mm thru 9.99mm

SIZE 10 = 10.00mm thru 10.99mm

SIZE 11 = 11.00mm thru 11.99mm

SIZE 12 = 12.00mm thru 12.99mm

SIZE 13 = 13.00mm thru 13.99mm

Example:
The 1st end of the glass tip has a diameter of 8.8mm
and the 2nd end of the glass tip has a diameter of 9.2mm
-> Assigned size: 9 <-

If there is a specific size you need for whatever reason, please e-mail us at info@twister-glas.de and we will do our best to accommodate specific size requests.