1. Spiral waterproof watch. Both the upper case and the back cover of the watch case are threaded. Relying on the function of the thread, the upper shell and the rear cover are tightly screwed together. Waterproof gaskets are placed in the upper handle and where the back cover and the upper case are screwed together. This waterproof watch has a notch on the outside of the back cover of the case. Some are polygonal convex parts. Corresponding tools must be used to switch the back cover.
2. Withhold type waterproof watch. There is a ring of high convex spigot inside its back cover. The upper case and back cover can be tightly buckled. The watch glass and spiral waterproof watch are also rolled in with tools, which is relatively tight. Waterproof gaskets are also placed in the upper part of the crown and where the upper shell contacts the back cover. The back cover of this waterproof watch is opened with a knife. The back cover is also pressed with a crimping tool or pushed and lifted with your fingers.
3. Sleeve pressure waterproof watch. The upper case of its case is pressed on the bottom cover. There is a higher wall around the back cover of this watch case, and the movement is installed inside the wall of the back cover. The watch glass is directly mounted on the surrounding wall of the back cover, and the upper case is pressed in. The watch glass and the back cover are tightly sheathed, thus playing a role of sealing and waterproofing. The winding stem is connected by two upper and lower sections. When opening and closing the back cover, first remove the winding crown and the upper winding stem. Press and tighten with special rolling tools.