Micro USB input: 5V 1A, Charging display: intelligent digital display, Screen size: 27mmx 17mm, Batteries Type: liquid lithium-ion batteries (18650) 3.7 lithium-ion battery only, USB Output: 5V 2.1A / 5V 1A(Dual USB interface), Product Size: 57mmx 28mm.
Get coupons, create price alert or check price history out! You probably want to know what is the 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 China.
Link: Banggood product page
1. ($6.27): Cuponation9
2. ($6.48): BG00c906
paste coupon code in your cart and click Apply 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): BGd0b05d, BG2589f4, 00c906, ADMITAD2212, 2022ACTIESNL, Terence, Tabby20, 8Couponsde, MVC8SPRING, BGJUNEGSG9
(these coupons are old, so probably won’t work)
Price history and price alert
Check out price history chart (for all/most countries) for Dual USB 5V 1A 2.1A Power Bank 18650 PCB Module Board. The lowest price was: $3.99.
Price records source(s): Banggood
Click on image to enlarge. 
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)).