$14.99 – Enclosure Material: Fire-retardant ABS V0, Security Mechanism: WPA-PSK/WPA2-PSK, Gang: 2, Color: White, Max Current: 15A(total) /10A(1 gang), Humidity: 5%-95%RH / Non-condensing, Frequency: 802.11 b/g/n, Operating Temperature: -10ºC-40ºC, Product Dimensions: 54*49*24mm, Power Supply: 100-240V AC, Max Power: 3300W(total) / 2200W(1 gang).
The coupon price for SONOFF DUALR3 Dual Relay Module Switch is $14.99 (in Banggood). Basically copy coupon, view price history or create e-mail price alert. Do you want to know what the best price is?
Latest coupon and price update (UTC):
Banggood ($14.99)
Banggood warehouse is located in China. There are no coupons available at this moment in Banggood. What about the price? From what I can see this price is higher than average price ($11.94).
Link: Banggood product page
Price: $14.99
Additional Banggood coupons: first page and second page
Old coupons (from the oldest to the newest): BGDUALR3, BGDUALR313, 13f142, BG36c08a, BGee1672, BG619c1a, 6GSGIT, ADMITAD2212, BGSmart6, 8Couponsde, MVC8SPRING, 8wEbgaInS5, pROMo8cuPoN, BGJUNEGSG9, BG15Sonoff, BG8ReviTrage, Cuponation9, 9OFFSUMMER, BG32140d
(these codes were not working in latest coupon update, but you can check them out anyway)
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. Europe – SONOFF DUALR3 Dual Relay Module Switch [EU] ($-3)
Aliexpress
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Price history and price alert
Here is price history (for all/most countries) for SONOFF DUALR3 Dual Relay Module Switch. The lowest price was: $9.99.
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)).