Charging USB charging, Size 40*34*34mm, Waterproof IP6, Battery 3.7V 400mAh Battery, Modes 3 modes (slow flashing – fast flashing – always bright), Material Aviation aluminum alloy, Weight 55g, Brand ANTUSI Q5.
Go down and check coupons out. Remember to check price history if it is available. 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 code price check (UTC time):
Banggood
Banggood warehouse is located in China. There are no active coupons for this product, but the price is pretty low isn’t it?
Link: Banggood product page
Price: $-3
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!
Additional Banggood coupons: first page and second page
Old coupons (from the oldest to the newest): 0e7f33, FBCOUPON1, BG77IK, BGAFF10OFF, BGCuponation10, 13f142, BGHONEY2110, BG10OFFAFF, BGwhielabel
(probably won’t work, but you can try them out)
Price history and price alert
Check out price history chart (for all/most countries) for ANTUSI Q5 Bicycle Brake Taillight. The lowest price was: $19.99.
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)).