About This May improve the hardness and durability of egg shells Gives the chickens the option to have more calcium if they need it. Safe option for roosters—does not force them to supplement with calcium if they don’t need it. Automatically refills the eating cup as needed. Saves time by not requiring frequent refilling. Installs easily. The back of feeders slip onto to the head of a screw. You can mount the screw onto any wood piece in the coop or run. Drainage holes allow water to drain while oyster shells/grit remain. Helps chickens digest their food so they get the nutrients they need Helpful for chickens who don’t free range Overview Brand : Revolutionary Chicken Target Species : Chickens Recommended Uses For Product : Feeding Station Material : Plastic Special Feature : Automatic Refill, Easy Installation, Drainage System