I was sceptical about buying this at first, but after having it for over 6 months I’ve found it to be a great way to store & play Gameboy roms on the go. For £30 I can play any .GB, .GBC, .GBA, & .NES rom on one cartridge via micro SD! (This includes GBA Video & rom hacks too). Games run flawlessly as whatever rom is selected from the SD card is loaded onto the ram of the cart itself, so there is no lag at all. Although, if you want to play Gameboy Color Games, beware. It saves games, but to a degree. If you save a game & then turn of your Gameboy straight away it will not save. If you exit straight after saving it will also not save. All it takes is for one human error to occur & you will loose all your game data. The ability to play NES roms is a really nice feature. The games will run fine except there are some pixel scaling issues considering the GBA pixel dimensions. You can also use hacks, save states, button auto-fire & Super Gameboy borders. GBA, GB games however work fine & overall I would highly recommend it!