Kaytee CritterTrail Fun Value Pack Straight Tubes

Q: How many pieces come in the value pack?

9 pieces: 4 connector rings, 2 - 3.5" tubes, 2 - 10" tubes, and 1 - 1.75" tube.

Q: I am looking for one of the 3.5 inch tubes that you can put in the top of a cage -- so it has the little ridges on it. Does this set include one?

Hi. No, I don't remember this having that 3.5 inch piece that you need. I would suggest you keep looking. It does exist out there. Good luck.

Q: Will this connect to the Habitrail? And if not, how can I connect a habitation and a crittertrail?

It'll connect to anything kaytee but they are just straight tubes that are pretty useless unless you have like two hamster cages to connect or a lot of other hamster accessories, other wise someone like me with only the one cage they were completely useless as there aren't even curved tubes to connect back to the same cage. Just some long and straight ones.

Q: Can you use this in a 10 gallon aquarium to create tubes for the hamster to run in?

You would need a way to suspend or attach these in the tank. There are connector rings to snap the tubes to themselves included, but nothing to attach the tubes to a glass tank. So if you wanted these tubes to lay on the floor (like toilet paper or paper towel tubes), then yes they can lay flat. I believe what you really are looking for is called a "tank topper", which is a complete kit to attach to the top of a glass aquarium to make it more interesting as a hamster habitat. Look into those.