Wireless tens placement?

Hello! I've been thinking about getting myself a tens unit since my life got busy. I searched the wiki and subreddit for tens recommendation and then went on a search for what's available in Poland. Wireless options caught my eye immediately; it's be the perfect solution for me but then Im wondering; how do you place them? The ones with wires go on both sides of your nipple(- on one and + on the other side) but wireless ones look like they have both + and - channel together? I'm so confused so if anyone used wireless ones I'd be grateful for advice!

The ones I found available if it helps;

https://www.amazon.com/Comfytemp-Wireless-Stimulator-Rechargeable-Control%EF%BC%884pads%EF%BC%89/dp/B0CLV5S4ZK

https://www.amazon.de/Schmerztherapie-Puersit-Reizstromger%C3%A4t-Trainingsger%C3%A4t-Schmerzlinderung/dp/B0CW9JB21P