These bee guards are replacement parts for the Perky Pet Pinch-Waist Hummingbird Feeder. Though I've never lost a bee guard yet, I got these as back-up replacements just in case.  The Pinch-Waist Feeder flower ports can be used with or without these bee guards.  But since we have a bee problem, we choose to use the bee guards to keep the insects out of the feeder reservoir base.  Before getting the Pinch-Waist Feeder with bee guards, our old feeders of a different style leaked badly and swarms of bees hung out and crawled inside the reservoirs and died.  These bee guards really work to keep out the insects and the hummies' are very adept at getting their long tongues through the bee guard grids to drink.  I love that the hummies can sip in peace without fighting off pesky insects.