Was the Ram Turbo the only 3rd party Interface 2 ROM cartridge interface for the ZX Spectrum or were there others?

One of the original Sinclair peripherals for the ZX Spectrum was the Interface 2 which provided joystick ports and also a slot for ROM cartridges:

The cartridges did not catch on though and only about 10 titles were ever released.

But before it was known that it would be a flop, at least one third party company released a compatible ROM cartridge interface, the Ram Turbo:

When I was a kid I bought a joystick and cartridge adaptor for my original 48K Speccy by mail order from the UK. I can’t remember which brand it was except that it was not the official Sinclair one. Maybe it was the Ram Turbo. But were there others on the market as well? I can’t find a definitive list and only some modern retro-era addons are turning up in my Google quest.