It means there is no LED included. It will just be empty and unlit. It probably won't have LED housings either so upgrading in the future if you want may require getting those also. The reason the other colors are not selectable is because they are mixed colors requiring multiple diodes each and enough to light the main and side blades with mixed colors depletes the batteries ridiculously fast. A simple after market battery upgrade does require wiring but can allow the mixed colors to work in all blades.
awesome, I had a feeling this was probably the case, good to know about the othe LED colour stuff, thanks for the help mate