For use with the 4" diameter Big Tube feeders. Also fits all Aspects 2-3/4" diameter standard tube feeders. The Super Tube Top is a clear dome molded of UV stabilized, super-tough polycarbonate and carries a lifetime guarantee. Featuring a large 18" diameter dome, this item offers superior protection against the elements and squirrels. The unique feature of the Tube Top is the proximity of the dome to the feeder. Simply place the Tube Top over the bail wire and rest it on the feeder's cap - no hardware needed!