Easy exercise equipment for the office: grip strengthener [My personal workout tool]

Due to the nature of my work at the office, I have to spend the entire day clicking a mouse and a keyboard, which puts a lot of strain on my fingers and wrists. Therefore, I exercise with a grip strengthener during breaks in my work hours to strengthen my hand grip and wrists. It is easy to find and relatively inexpensive, but I rarely see people around me exercising with a grip strengthener. In my case, it is very effective.