Some portable CD players are more rugged than others, but they're still far from indestructible. While most should be able to withstand a few bumps, be careful not to drop them from any height, as it's likely they'll break or at least suffer some nasty scrapes. With the exception of some weather-resistant models, most portable CD players don't take kindly to getting wet, so stow yours away safely if you're using it outside and it starts to rain.