You want to wear sunglasses to keep out the glare when shopping, eating out or just taking a stroll around the block.  But you also need your readers to see your phone, price tags, menus and other small print.  Switching between sunglasses and readers slows you down and is a hassle.  Plus the whole reason you wear your sunglasses is to keep out the glare.  Sticktite lenses stick near-instantly to the inside of your sunglasses and convert them to readers.