Review on Hydrotac Bifocal 20 3 00 Diopter by Rashad Ross

They work well in my snorkel mask. I bought +3 to be able to read the fine print on my dive computer. After cutting them to shape, aligning them and sticking them on, I found that they allowed me to read fine print and didn't interfere with my normal distance vision. The photos show where I cropped them to fit my lenses. Cropping was essential to getting them where I needed to really see through them. They can easily be trimmed with sharp scissors. Installation Tips: Install dry and mark with a trim marker before installation. Make sure they are aligned vertically with your eye but below your eye. I found it easiest to submerge the mask and lens in water, then position the lens and press on it all the time underwater so no air can get trapped. Lenses are flexible, but not infinitely flexible. They will not work on a flat mask or an unusually curved mask. I've had the 5.5 and 6.5, and the 6.5 had more problems with air pockets when trying to glue above water (hence the underwater glueing technique). Exams. Results: I washed them with: soap, salt water, anti-fog mask, fresh water, pool water and saliva. They stayed stuck and in place - I've snorkeled and cleaned it many times. I even took it off clean and rubbed the inside with my fingers (under water). They stayed glued and in place. I left the mask in the sun for several hours. No noticeable effect. - I swam 1.5km to see if they would fog up any differently than the mask itself. They didn't sweat any differently. Bottom line, I would recommend them for use in a prescription SCUBA mask to create a bifocal mask.