Compatible OS Android 4.4 or above; iOS 8.0 or above, Bluetooth Version BT 5.0, Operating Mode Full-Touch, Model LF28 Pro, APP Name Dafit, Brand LEMFO, Flash 64M.
Basically copy coupon, view price history or create e-mail price alert. What is 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. ($49.84): BGc70579
2. ($49.84): BGbf11dd
this code has to be applied in your 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): BG1c50fe
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Here is price history (for all/most countries) for LEMFO LF28 Pro Smart Watch. The lowest price was: $39.99.
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)).