The black ones are stronger, this is what you will receive if you don't make a specification.

The beige colored ones are made with wood-based PLA plastic that isn't as strong, some people are finding they break on stiff shopping cart locks. If you want this option, please include a note when purchasing.

(I'm still using my original wood-based key! The way to not break it is not push from the handle but up near to the coin-shaped end.)