Output Current 0.5A/1A, Compatible with LiFePO4 / 3.7V/3.85V Li-ion / Ni-MH / Ni-Cd, USB port output 5V/1A, Input Power Micro USB DC 5V/2A, Output Voltage 4.35V/4.2V/3.65V/1.48V ±1%, Size 115mm×63.5mm×29mm (Length/Width/ Height).
You can create price alert here, copy coupons and view price history. 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 coupon and price update (UTC):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
1. ($18.65): FIN9777
2. ($19.85): BGAlerabatI
3. ($19.99): BG0b49b5
4. ($20.30): BGtorch2
apply code in your basket (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): BGAlerabat15, BGtorch7
(I don’t think these’re gonna work, but you can try ’em out anyway)
Price history and price alert
Do you need price history chart (for all/most countries) for KLARUS K2 Battery Charger? There we go. The lowest price was: $18.65.
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)).