Pretty tough actually. You know it’s a quality product when it’s 25 years old, and can still work, even after being frozen, submerged in alcohol, dropped from a two story building, and run over by car. By “quality”, I’m talking about the plastic cartridge, not the actual games. Seeing how the majority of NES games are abominations, and do not deserve the Nintendo “Seal of Quality” that they flaunt deceivingly on their stickers.