Basically copy coupon, view price history or create e-mail price alert. Best price?
Color: White, Security Mechanism: WPA-PSK/WPA2-PSK, Enclosure Material: Fire-retardant ABS V0, Max Current: 15A(total) /10A(1 gang), Humidity: 5%-95%RH / Non-condensing, Gang: 2, Max Power: 3300W(total) / 2200W(1 gang), Frequency: 802.11 b/g/n, Product Dimensions: 54*49*24mm, Power Supply: 100-240V AC, Operating Temperature: -10ºC-40ºC
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 
. Hmmm… There is no active coupon in Banggood at this moment. I can’t tell you if this price is good – not enough records in my database, so I won’t judge.
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!
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BGDUALR3, BGDUALR313, 13f142, BG36c08a, BGee1672, BG619c1a, 6GSGIT, ADMITAD2212, BGSmart6, 8Couponsde, MVC8SPRING, 8wEbgaInS5, pROMo8cuPoN, BGJUNEGSG9, BG15Sonoff, BG8ReviTrage, Cuponation9, 9OFFSUMMER, BG32140d
(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 – SONOFF DUALR3 Dual Relay Module Switch ($13.99)
Price history and price alert
Well, you won’t see price history chart, coz we have only 1 database record for this item (and price was $12.99).
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)).