Feature:1. Super soft and flexible O‑ring, easy to install, used to keep watches waterproof, prevent water getting into watch.2. Including different sizes can meet different size requirements, flexible, wear‑resistant and durable, high elasticity and reliable in use.3. O‑ring rubber gaskets last a long time and you don't have to worry about durability.4. Compact and lightweight design makes rubber watch rings easy to store without taking up too much space.5. Storing in a labeled and organized box, no need for sorting and sizing, very easy and convenient to use.How to Use:Remove the watch back cover and install the waterproof ring.Specification:Item Type: Watch Crown O‑RingMaterial: Rubber, Plastic Applicable Crowd: Suitable for watch maintenance professionalsApplication Scenario: Used to keep the watch level waterproof, prevent water getting into watchSize: Approx. 0.3 x 0.35mm / 0.01 x 0.01in 0.35 x 0.4mm / 0.01 x 0.02in 0.4 x 0.45mm / 0.02 x 0.02in 0.45 x 0.3mm / 0.02 x 0.01in 0.45 x 0.45mm / 0.02 x 0.02in 0.45 x 0.5mm / 0.02 x 0.02in 0.5 x 0.4mm / 0.02 x 0.02in 0.5 x 0.45mm / 0.02 x 0.02in 0.55 x 0.4mm / 0.02 x 0.02in 0.55 x 0.6mm / 0.02 x 0.02in 0.6 x 0.4mm / 0.02 x 0.02in 0.6 x 0.45mm / 0.02 x 0.02in 0.6 x 0.55mm / 0.02 x 0.02in 0.6 x 0.6mm / 0.02 x 0.02in 0.61 x 0.31mm / 0.02 x 0.01in 0.65 x 0.4mm / 0.03 x 0.02in 0.7 x 0.4mm / 0.03 x 0.02in 0.7 x 0.45mm / 0.03 x 0.02in 0.7 x 0.55mm / 0.03 x 0.02in 0.7 x 0.6mm / 0.03 x 0.02in 0.4 x 0.4mm / 0.02 x 0.02in 0.6 x 0.5mm / 0.02 x 0.02in 0.45 x 0.4mm / 0.02 x 0.02in 0.6 x 0.65mm / 0.02 x 0.03in 0.5 x 0.3mm / 0.02 x 0.01in 0.65 x 0.7mm / 0.03 x 0.03in 0.5 x 0.5mm / 0.02 x 0.02in 0.7 x 0.5mm / 0.03 x 0.02in 0.6 x 0.35mm / 0.02 x 0.01in 0.75 x 0.5mm / 0.0