If you make your own fertilizer pellets or cakes then these are the baskets for you.
Placing fertilizer directly onto the surface around your bonsai tree you will stunt the growth of moss or even kill it. These containers are designed to hold most fertilizer whether granular or pellet, elevating the fertilizer from the surface of your soil reducing the stunting effect on moss.
The "fingers" reduce loss of fertilizer through watering or being eaten by birds, rats or other animals.
The colour allows it to blend aesthetically as well.