Pine Siskins (PISI) or House Finches (HOFI).
As a result, we have updated our Disclaimer and Product Pages to better illustrate HOSP and how to identify them. We urge folks to read about the Pine Siskins and what is going on with that species (among others) and why they are suddenly "mobbing" feeders in the U.S.
The above said, we have been up front at all times that the Magic Halo isn't necessarily HOSP-proof. Our position is that it is a deterrent -- a tool in the anti-HOSP toolbox -- and at the very least, it should reduce them at bird feeders. We encourage folks to read our 2020 survey data and customer feedback and draw your own conclusions before buying a Magic Halo. Thank you so much.
(below is courtesy of Bayou City Birding, and can be found HERE in pdf)