Kaytee CritterTrail Fun-nels 10-Inch Straight Tube - Assorted Colors Ten-inch-long straight Fun-nel Tube and Connector Ring is used to expand any CritterTrail habitat Easily connects to any CritterTrail habitat port and other Fun-nels tubes and accessories to expand your pet's living space Durable 10-inch-long plastic tube snaps apart for easy cleaning and includes a connector ring for easy attachment to other CritterTrail components Each tube has ventilation holes for your pet's safety 10-inch-long tube is 2.25 inches in diameter