For beginners a full face snorkel mask can really be a boon. There is no learning curve or getting comfortable breathing through your mouth. You simply put it on and breathe normally. How To Wear Snorkel Mask for Adults: 1. Install the breathing tube on the snorkel mask.2. Install the removable action camera mount on the tube, then fix the camera tightly on the mount.3. Put on the mask and adjust the length of the elastic bands, please make sure there is no gap between the mask and your face. What size should I choose for swimming diving mask ? Step 1. Measure the distance between the bridge of your nose and the bottom of your chin.Step 2. If the distance is 8-10cm, choose XS.If the distance is 10-12cm, choose S/M.If the distance is 12-14, choose L/XL. Warnings: 1.Not suitable for children under 14 years and must be strictly under parent supervision only .2. The snorkeling mask is for snorkeling only, please don't dive into free diving,scuba diving or strenuous swimming.3. Just leave it dry naturally after cleaning mask with fresh water to avoid direct sunlight and use glasses cloth to clean the face lens, don't use towel.4.It maybe a little fog if the temperature is more than 40℃, if the fogging is heavy, please make sure there is no gap between the mask and the bridge of your nose, or the exhaled gas will cause air mixture and fogging issues.