Operating Mode Full Touch Screen, Bluetooth Version BT5.2, Compatible OS Android 6.0 or above; iOS 10.0 or above, APP Name Mi Fitness, Brand Xiaomi, Model S1 Active.
Check coupons or create price alert down below. You probably want to know 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 Hong Kong. Coupons for Xiaomi S1 Active Smart Watch? Nope, there’re no coupons in Banggood.
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): BGS1ACT, BGc70579, BGS1ACT2, BG4eddff, BGHOBBY17, BGJPS1AT, BG8a0c47, BGHUXC152, BGDealkal06, BGJP61702, BG6a0c34, BGacef4f, BG1f8881, BG72c255, BGbf11dd, BGBRS1A, BGHU2380, BG9f930a, BG8a367f, BG811b36
(these coupons are old, so probably won’t work)
Price history and price alert
Here is price history (for all/most countries) for Xiaomi S1 Active Smart Watch. The lowest price was: $119.99.
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)).