These handy feeders turn any bottle with a thread size of 25mm into a bird seed feeder. Sold in a great value set of 3, they are easy to attach, you simply cut the base off the bottle, carefully cut 2 incisions to hold the plastic hanger, and screw in the feeding base. Simple to use and very cost effective to keep wild birds fed through the cold winter months - homemade bird feeders have never been easier to make.