This item: SCORE One Tennis Lite Scorekeeper. $2650. +. Scoring Right Portable Tennis Racket and Padel Scorekeeper, Easily Mounted Small Score Board to Keep Score of Points, Games, and Sets, ITF Conforming and Lightweight Mini Score Keeper, 1.9g. $1495.
https://www.amazon.com/Score-One-Tennis-Lite-Scorekeeper/dp/B0006GRM18