Specifications:
Material: High quality rubber
Thickness: 1.25mm
Use on: 1.5mm thick watch crystal glass
Quantity: 49 sizes, 2 pieces for each size, 98 pieces in total

Diameter(O.D. X I. D) unit: mm
16.8 x 16.0 21.8 x 21.0 26.8 x 26.0 31.8 x 31.0 36.8 x 36.0
17.3 x 16.5 22.3 x 21.5 27.3 x 26.5 32.3 x 31.5 37.3 x 36.5
17.8 x 17.0 22.8 x 22.0 27.8 x 27.0 32.8 x 32.0 37.8 x 37.0
18.3 x 17.5 23.3 x 22.5 28.3 x 27.5 33.3 x 32.5 38.3 x 37.5
18.8 x 18.0 23.8 x 23.0 28.8 x 28.0 33.8 x 33.0 38.8 x 38.0
19.3 x 18.5 24.3 x 23.5 29.3 x 28.5 34.3 x 33.5 39.3 x 38.5
19.8 x 19.0 24.8 x 24.0 29.8 x 29.0 34.8 x 34.0 39.8 x 39.0
20.3 x 19.5 25.3 x 24.5 30.3 x 29.5 35.3 x 34.5 40.3 x 39.5
20.8 x 20.0 25.8 x 25.0 30.8 x 30.0 35.8 x 35.0 40.8 x 40.0
21.3 x 20.5 26.3 x 25.5 31.3 x 30.5 36.3 x 35.5

What's included:
1 Set Waterproof O-ring