Aliexpress
Click here… to search for Usmile 4Pcs Soft Grey Electric Toothbrush Heads on Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China. So I have checked for active coupons (all category coupons and old ones), but there was no working coupon in Banggood.
Link: Banggood product page
Price: -3 USD
It looks like this item is out of stock in Banggood. If you found it then please send me the link. I will replace it.
Click here to search on Banggood!
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): BGd9abff, BG75597c, BGaf7ff1, BG589b2e
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Price history and price alert
Do you need price history chart (for all/most countries) for Usmile 4Pcs Soft Grey Electric Toothbrush Heads? There we go.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).