October 14, 2021
Dunlop 220 packaging specs are close. Mine is 18.9 mm inside instead of 19mm. Exterior is 21.9 mm, so walls are 1.5 mm as stated on the packaging. It is 60.3 mm long. Ring size 9.
I also have a Dunlop Glass 202. Mine is 17.8 mm inside instead of 18mm. Exterior is 21.8 mm, so walls are 2 mm as stated on the packaging. It is 68.7 mm long. Ring size 8.