Standby Time: About 40 days, Resolution: 240*240pixels, APP Name DaFit, Charging Time: About 2.5 hours, Type: TFT, Battery Capacity: 280mAh, Charging Type: Magnetic Charging, Size: 1.3inch, Bluetooth Version BT 5.0, Personalized Watch Face Support, Blood Oxygen Monitor Support, Waterproof 5ATM Waterproof, Using time: About 15 days.
Go down and check coupons out. Remember to check price history if it is available. Let’s see what best price is ATM.
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 Hong Kong.
Link: Banggood product page
1. ($17.99): BG8a509b
2. ($40.24): BGc70579
apply code in your basket (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): band10, BGWRIBAND10, BGb58412, BG51f436
(there’s a little possibility that old coupon will work)
Price history and price alert
Here is price history (for all/most countries) for UMIDIGI Uwatch 3S Fitness Tracker. The lowest price was: $17.99.
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)).