CritterTrail Fun-nel Tubes attach directly to each other and to the inside and outside of your CritterTrail home. If you can imagine it, you can build it with CritterTrail Fun-nels! The tubes are available in four colors and in a variety of shapes and sizes so you can create a huge playground for your pet. Our Fun-nels U-Turn provides a perfect 180 degree twist into your Critters tube city. With CritterTrail Accessories, your imagination is your only limit. For: Hamsters Mice & Gerbils