If you can call him, tell him to get both
3/8" I.D. - 1/2" O.D. - 1/16" W
and
7/32" I.D. - 11/32 O.D. - 1/16" W
The smaller of the two doesn't fit snugly in the cap and tends to fall out when swapping bottles, but it forms a good seal without bunching up.
3/8" I.D. - 1/2" O.D. - 1/16" W
and
7/32" I.D. - 11/32 O.D. - 1/16" W
The smaller of the two doesn't fit snugly in the cap and tends to fall out when swapping bottles, but it forms a good seal without bunching up.