Without any more context, this could be a simple vest with a pocket to fit a pod, or a full GPS built-in vest. I would use simply the word "vest", as there is no enough info to decide either way, and to describe it further (like GPS vests, etc). If you read the word vest next to computer and software, and rubgy, you understand it is IT related. If you've got more context, use the phrase tracker vests.

https://eu.shop.statsports.com/collections/apex-athlete/prod...

http://mac-lloyd.com/produits/#!/stade
brassières avec poches
vests with pockets


Le capteur est intégré à une brassière e-textile que l'on porte à l'entraînement et pendant les matchs à l'extérieur ou à l'intérieur.
http://www.connectedperf.com/accueil/category/aviron

It is a standalone device worn on a player’s back to collect statistics, which are synchronized at the end of the game or practice.
https://www.benesportsmedical.co.nz/shop/EquipmentBags/Field...