Nay-say all you want but "what's the score?" when you play with a group of chatty tennis pals, is a very common query. A point tool could come in handy.
The watch (it does tell time as well) is lightweight, water and sunscreen resistant, and, because it is close fitting, it does not get in the way or move around.
ScoreBand is $30.00 USD and comes in a variety of sizes and colors. It can be used for other sports as well.
Find it at ScoreBand.net