Product Highlight(s): Super Pet CritterTrail Bubble Wave Fun-nels Connectable Tube for Critters (3-1/2 Inch) Stock up on these 3-1/2" sections to be creative and make a cool home for your gerbil, hamster, mouse or rat. Crittertrail tubes attach to all crittertrail cages. Please note: Color specification is unavailable on this item