Go down and check coupons out. Remember to check price history if it is available. Best price?
diameter 10mm, Operating environment: -10℃-50℃ (14℉-122℉), Emission current: ≤10mA, Quiescent current: ≤5μA, Product Size: 77*49.5*18.8mm, Weight: 45g, Protocol: EV1527, Wireless frequency: 433.92MHz, this package doesn’t come with the battery., Battery: length 27mm, Support Battery: 12V 23A
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in Europe 
. Well, there is one coupon available right now.
Link: Banggood product page
1. ($21.67): 13f142
you should apply the coupon in your cart after clicking “Proceed to checkout”. Click to copy code and open shop)
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): elec, BGVDay10%off, 0e7f33, FBCOUPON1, bGhOnEy10, BGSMOFF, BGSONOFF15, BGSONOFF16, BGSTHO15, BGHONEY2110, BGSHOM15, BGSHE15, 6GSGIT
(these codes were not working in latest coupon update, but you can check them out anyway)
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. China – 5Pcs SONOFF DW1 433Mhz Door Window Sensor ($-3)
Price history and price alert
Here is price history (for all/most countries) for 5Pcs SONOFF DW1 433Mhz Door Window Sensor [EU/UK].
Price records source(s): Banggood
Click on image to enlarge. ![Price history for 5Pcs SONOFF DW1 433Mhz Door Window Sensor [EU/UK]](https://couponsfromchina.com/pricehistory/History19451.png "5Pcs SONOFF DW1 433Mhz Door Window Sensor [EU/UK] price history")
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)).