The Kaytee CritterTrail Fun-Nel Tube Elbow is a great way to add more fun to your life with your pets. This elbow features a connector ring that allows you to easily connect to any other tubes or accessories. The tube is made of plastic for durability and easy cleaning. The ventilation holes provide safety for your pets. The tube is 2.25 inches in diameter for small animals like hamsters, gerbils, or mice.