Aliexpress
Click here… to search for 2×19.7mm Lumintop Self Illuminate Turboglow Flashlight Gasket on Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
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): BGLMTB, FIN1856, BGwhielabel, 4BLF, BG10OFFAFF1, BANGGOODSD, 6GSGIT, BGTorch4, 00c906, BGtorch2, BGAlerabat15, BGtorch7, BGAlerabatI, BGtorch9, BG8Alerabat, BGLED07, BGOutlight10
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Price history and price alert
Here is price history (for all/most countries) for 2×19.7mm Lumintop Self Illuminate Turboglow Flashlight Gasket.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).