When I was updating this page, then coupon price was $15.99 for Rechargeable Magnetic Hand Warmer (in Banggood). You can create price alert here, copy coupons and view price history. You probably want to know what is the best price?
Latest coupon code price check (UTC time):
Rechargeable Magnetic Hand Warmer 2 in 1 Smart Dual-Sided Hand Heater Quick Heating 45/55/60°C Pocket Heater for Warm Gifts – Black
Banggood ($15.99)
Banggood warehouse is located in China. Low/high price? Actually this is the best price in history according to CouponsFromChina database! I found coupon for you. Check this out.
Link: Banggood product page
Price without coupon: $16.99
1. ($15.99): BGd84c76
just apply this code in your cart after clicking “Proceed to checkout”. Click to copy code and open shop.
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Price history and price alert
Do you need price history chart (for all/most countries) for Rechargeable Magnetic Hand Warmer? There we go.
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)).