CoolFun design keeps pets entertained and enriches their environment by providing new and different places to play and hide.Compatible & ConnectableUniversally connects to all CritterTrail, Habitrail, and S.A.M. systems.ColorfulHas fun colors kids love and dark translucent colors for your critter's comfort. Includes:1-Loop-D-Loop1-Outhouse1-Snap-On Comfort Wheel1-Fun-nel J-Tube1- Bubble Plug1- Fun-nel Tee1- 3.5" Fun-nel Tube4- Connector Rings Start Collecting and Connecting Today