Yes it is, from the googling I have done and what most people think who have seen it, it may be a homebrew dev cart.
Im wondering if it would sell for much on ebay.
It's a home made flash cart.
You burn game roms onto an eprom chip and connect them to
that cartridge to play them on the console.
The switch on the top allows you to use either 2K or 4K eprom chips.