We love the entire line of Mr. Bird products for many reasons. These cylinders are made up of compressed, high quality seeds and nuts. Each cylinder has a hole in the middle for mounting onto a holder (sold here) or you can simply set it out on an open tray. The feature that we love the most about these products is that you don't get nearly the waste of a traditional seed feeder and there is hardly any mess on the ground. You don't have to worry about filling a feeder daily (a nice feature if you're gone for a few days.)
Birds love all varieties of Mr. Bird products so you might want to experiment
with the different varieties to see what works best in your yard. We
are always amazed at the variety of birds that will show up to eat at
these blocks.