Name Door and window opening and closing sensor, Color White, Weight Body 6g (excluding battery) / Magnet 7g, Battery type CR1632 button battery, Size Body 44×21.5x13mm /Magnet: 29x14x7mm, Model CGH1, Bluetooth specification Low Power Bluetooth 5.0.
Price history, coupons and price alert are available on this page. You probably want to know what is the best price?
Aliexpress
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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. I’m afraid that there’s no working coupon 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): BGFETD143, BGAFF10OFF, BGQPDW, BGSTHO15, BGHONEY2110, BGSHOM15, 13f142, BGSHE15, BG8b6be7, BG7d441e, ADMITAD2212, BGSmart6, MVC8SPRING, 8BGwbg2204, 2203ActiesNL, tRaDetRaCKeR, 8wEbgaInS5, pROMo8cuPoN, BGJUNEGSG9, Cuponation9, 9OFFSUMMER
(these coupons are old, so probably won’t work)
Price history and price alert
Here is price history (for all/most countries) for ClearGrass CGH1 Qingping Window Door Sensor. The lowest price was: $4.99.
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)).