1pc Square calendar Sapphire Bubble Magnifier Lens Suitable For Date Window High Transparency Watch Crystal Glass 7.0x5.5mm etc. Optional size reference: General square calendar window choose square calendar crystal, round calendar window choose round calendar crystal, or choose according to your own preferences. The choice of general glass diameter above 28mm [square 7.0x5.5mm large]; Glass diameter 21-28mm selection [square 5.5x4.5mm small size] Please choose the calendar grain size based on the actual size of your watch. The above options are for reference only. Instructions: 1. Clean the watch glass and calendar crystal. 2. Coat the bottom of the calendar crystal with shadowless adhesive (ultraviolet adhesive). It should not be applied too thickly. Place the calendar crystal grain above the position of the watch glass on the watch calendar display to a good position. 3. If the position is not right, do not use the purple light (ultraviolet light) first, you can adjust the position of the calendar crystal, if there is excess adhesive overflow, wipe it off in time. 4. After confirming that the calendar crystal is placed in the correct position and no adhesive overflows, irradiate it with a purple light (ultraviolet light) for about 15 seconds. 5. The adhesive is solidified and the installation is complete. Precautions: The above reference step uses UV shadowless adhesive (ultraviolet adhesive), which is transparent and traceless after drying. If the position of the calendar crystal is wrong, don't light up Before illumination, it can be adjusted at will, and the adhesive is non-sticky. After lighting the lamp, the adhesive will solidify and cannot be adjusted If the glue overflows, you can wipe it off before illumination. It will solidify after been illuminated. You can only scrape off the overflowed adhesive bit by bit with a cutter or wipe it off with alcohol. Package included: 1*Square/Round calendar lens