Features:1. Rubber O-Ring watch gasket used to keep your watch water resistant.2. Made of rubber material, flexible and wear-resistant, durable to use.3. The crown o-ring is good accessory for watch repairing.4. Suitable for watchmakers and watch repairing workers to use.5. Having excellent workmanship and suitable for various of watches. Specifications:Item Type: Watch Crown O-RingMaterial: RubberFunction: Watch Repairing AccessoryContains 10 popular size (unit: mm) :1.4x0.6x0.41.5x0.6x0.71.6x0.6x0.51.7x0.7x0.51.8x0.8x0.51.9x0.8x0.72.4x1.4x0.52.8x1.75x0.533.2x1.8x0.73.6x1.7x0.8 ( Each size including about 50pcs )Package Included:1 x Box of Waterproof Seal