Kaytee CritterTrail Assorted 3.5" T-Tube Replacement Tube Each tube has cross ventilation holes to provide pets with adequate air flow Easy to climb bubble wave design makes climbing safe, secure and comfortable Connector rings snap on easily for a safe and secure fit and release easily for simple disassembly and cleaning Ideal for hamsters, gerbils or mice Buyer will receive one (1) T-Tube in a random color.