When big birds dominate your platforms and tube feeders, small songbirds can feed here. This clever duncraft feeder uses black oil sunflower seed only. Only certain birds like chickadees, nuthatches, titmice, and gold finches have the ability to cling. Nurture clinging type birds. Dimensions are 6.25 X 6.25 X 4.75 UPC Code = 742933350011