They appear to use 2 AAA batteries.
Please let me know when you can pick at the Ohlone College Starbucks.
Google Map pin to get to Ohlone College Starbucks:
https://maps.app.goo.gl/kPezoxqSohTABEPe7
2 battery powered bike taillights
This offer has been gifted to someone and is no longer available.