Small Sonoff like the Sonoff mini - fits in US junction box.
DIY Smart Switches - SONOFF Official
smart switch - Sonoff Mini with Home Accessory Architect firmware - Home Improvement Stack Exchange
SONOFF MINI - Two Way Smart Switch ( sonoff tutorial ) #14
SONOFF Mini R2 10A Smart WiFi Wireless Light Switch, Universal DIY Module for Smart Home Automation Solution, Works with Alexa & Google Home
Sonoff Mini Two Way WiFi Smart Switch Installation Guide
SONOFF ZBMINIL2 Extreme Zigbee Smart Light Switch (2 Way), Compatible with Alexa, SmartThings Hub, Google Home&SONOFF ZBBridge-P, ZigBee Hub Required, No Neutral Required 4-Pack
1/30 Pcs Sonoff Mini Wifi Switch R2 Diy Two Way Smart Switch Relay Module Wireless Switch Smart Home Automation Work For Ewelink - Automation Modules - AliExpress
SONOFF MINI DIY Two Way Smart Switch WiFi - NEW 4 Packs
Sonoff Mini - make your old light switches smart
Sonoff Mini R2 - small WiFi smart relay switch with DIY mode (REST API) - eWelink Store
MINIR4 - SONOFF Official