Size: 48*29*10mm (length * width * height), Voltage range: 2-3S, Weight: 9g (excluding adapter cable).
Basically copy coupon, view price history or create e-mail price alert. 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 and price update (UTC):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
1. ($13.00): BGJUNEGSG9
2. ($13.15): BGJON8
3. ($13.15): BGRCParts8
just apply this code in your cart after clicking “Proceed to checkout”. Click to copy code and open shop.
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/i1u
Old coupons (from the oldest to the newest): BGYIIL, bgshOOp10, BGRC902, bGhOnEy10, BGHALLOWEEN, BGTT10, Parts8, 13f142, BGCuponation10, BGDAVIS, BG2e251c, BGe5a1ac, 8Couponsde, MVC8SPRING, tRaDetRaCKeR, 8wEbgaInS5, pROMo8cuPoN, BG8RCToy, BGRCT10, TTSUMMER8, Cuponation9, BGMatt2022, BGToys8, BG25d4e7
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. Europe – URUAV Sentinel S02 RC Battery Low Voltage Alarm [EU] ($-3)
Price history and price alert
Price history (for all/most countries) for URUAV Sentinel S02 RC Battery Low Voltage Alarm is here. The lowest price was: $5.5.
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)).