Bio-degradable BBs are good for the environment. If you play on private property or in your own back yard, the last thing you want is a field riddled with BBs. These bio BBs are water soluble and turn into powder form after being soaked in rain and heated in the sun. Save the environment and don't litter!
Please note that Excel have a typical actual size of 5.91 mm, while most other brands are 5.95 mm. This can affect the operation in some models that feed from a double row (like the KSC M11 and similar models).