1. Spiral waterproof watch. The upper case and the back cover of the watch case have threads, and the upper case and the back cover are tightly screwed together by the action of the threads. The watch glass is rolled and pressed in with tools, which is relatively tight. Waterproof gaskets are placed in the winding crown and where the back cover and the upper case are screwed together, so it can play a certain waterproof role. This waterproof watch has a notch on the outside of the back cover of the case, and some has a polygonal convex part. Corresponding tools must be used to switch the back cover.

2. Snap-on waterproof watch. Its back cover has a circle of high convex sub-ports, so that the upper case and the back cover can be tightly buckled. The watch glass and the screw-type waterproof watch are also pressed in with tools, which are relatively tight. Waterproof gaskets are also placed in the winding crown and where the upper case contacts the back cover. 3. Case-pressed waterproof watch. Its case upper cover is pressed against the bottom cover. The shape of the back cover of this watch case is quite special: there is a high surrounding wall around it, the movement is installed in the surrounding wall of the back cover, the watch glass is directly installed on the surrounding wall of the back cover, and the upper case is pressed into the back cover. , the watch glass and the back cover are tightly covered, so as to play the role of sealing and waterproofing.