Voltage: 5V.
You can create price alert here, copy coupons and view price history. What is best price?
Aliexpress
There’re some similar (or not) items on Aliexpress
You can use link bot to get even lower price:
Click here to search by yourself. Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in Europe 
. I don’t know if this is a good price – number of records in my database is too low!
Link: Banggood product page
1. ($21.85): tRaDetRaCKeR
2. ($21.85): 8wEbgaInS5
3. ($22.09): 2203ActiesNL
this code has to be applied in your cart after clicking “Proceed to checkout”. Click to copy code and open shop.
Additional Banggood coupons: first page and second page
Old coupons (from the oldest to the newest): BGLED2203, MVC8SPRING, 8BGwbg2204
(there’s a little possibility that old coupon will work)
Price history and price alert
Not enough data to show price history chart… $20.9 is the only recorded price. It was not cheaper than that since we have saved it in DB.
You can set price alert (for Banggood and Aliexpress (only if product name will be the same as on Banggood and I will post it on social media though, so it’s more like Banggood price alert)).