Interpet Limited Superpet Critter Funn Tube (Assorted Colors) Mixed, , Three-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 3-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 3-inch-long tube is 2.25 inches in diameter Three-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 3-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 3-inch-long tube is 2.25 inches in diameter Kaytee, formerly Super Pet