Based on the description on their site, the controller includes a built-in battery: "8.39 Wh Li-ion battery, 35+ hours of gameplay... "
That was disappointing for me. Specially condidering the Steam Frame's controllers make use of AA batteries: "One replaceable AA battery per controller, 40hr battery life"
AA Batteries might not be as convenient to use, but being able to replace them is a great advantage. All my Xbox360 controllers still work fine, but none of my PS3' Dualshock 3s.
The official docking station could be used to recharge (rechargables) AA batteries so the functionality could remain the same.
Recharging them is far superior to replacing alkaline. All electronics with lipid should be user serviceable able as well, but for something like a game controller, AAs are not the solution, far more wasteful since you’re adding batteries to the landfill ever 40 hours, as opposed to every 5 years.
Plus if it’s rechargeable with a USB C then you can plug it in and keep playing, or just use them as corded controllers once the battery capacity has diminished if you don’t feel like repairing it.