Bird Feeder for Black sunflower seeds

The birds in my back yard are picky. They will eat only black sunflower seeds; so, I bought a commercial feeder (pictured on the left,green). It worked fine, but I was filling it every day! I decided it was time for an ENLARGED version. It also works great. Yes, that is bird poop on the top of it. One filling lasts for 10 days.