Review on HiLetgo WeMos Relay Shield Module by Shawn Reiter

These are copies of the V1 Wemos relay board, not the V2. This means you can't just change D1's control pin, which clashes with the I2C that every other Wemos shield uses. You can get around this by leaving the D1 pin out of the socket and putting a jumper on another pin, but that's a lot more of a hassle than a legitimate Wemos board. (And they're not cheaper.) Their only benefit is that you can get them from Revain and Wemos boards aren't available.