What the hell. What is the difference? I wonder what I have.
The US version has Sega Master System 8-Bit Cartridge written at the top. The European version just says Sega at the top. Also, the US version has a little yellow strip across the bottm right that says it works on the Master System, the Master System II, and the Genesis Power Base Converter.
You can see a picture
hereI paid $35 for it from a private collector. It's not worth a ton, but I assure you it's hard to get the US version.