Hang this device on shepherds hooks or poles up to 2" in diameter to help discourage squirrels from reaching your birdfeeders. This model is for use with single - arm shepherds hooks or poles. Expands up to 48" in length to keep the squirrels on the ground and your bird feeder Squirrel Proof. The spring wraps around the hook or pole, making it more difficult for the squirrels to climb.