Did you know that some of the most common items we use every day are working double duty? Here are some objects that have hidden features that make life a little easier. The raised bumps on the F and J keys help you position your hands correctly without looking at the keyboard. The tiny hole in padlocks helps drain water and provides a spot for lubricant if the lock starts sticking. The black dots around a windshield help protect the adhesive that holds the glass in place.