Most recreational vehicles such as caravans, motorhomes and campertrailers are wired for 240v. They have a 15A connection to receive 240v.
This is fine when using caravans parks etc, as they usually have 15A sockets.
The problem is when you only have a 10A socket and need to plug into 240v power. 15A plugs have a wider earth pin than the 10A plugs. This means that you can plug a 10A plug into a 15A socket, but can’t plug a 15A plug into a 10A socket.
There are a couple of options to overcome this. They must have a 10A RCD fitted.
The Ampfibian is sold as a safe and legal way to connect a 15A RV to a 10A supply. It includes a 10A RCD (Residual Current Device).
Portable RCD with 15A to 10A Mains Plug Conversion
The Jaycar MS4044 does the same as the Amphibian, however, it is not weatherproof. It is not to be used in rain or exposed to the weather.
Aldi every now and then sells a product similar to the Amphibian.