I clip these timer images into picture schedules for my young students with special needs. When paired with a real visual timer, kids began to get an idea of how much time each activity will take. This method is especially effective for children with Autism and others who struggle with transitions (it helps them realize that a nonpreferred activity will not last forever, and gives them warning as a preferred activity comes to a close). I am uploading them in word, so you can copy, paste and resize as needed.
EDIT:- I added several more