Hamster Cage Ventilation System for Habitrail Cages

You can use this to mount 4cm x 4cm fans to a Habitrail cage and keep your hamster more cozy. One of these per single cage seems to work fine. I have two cages that I've attached together with extra pieces, so I've made up two fans. Works really well. Keeps temperatures more even inside the cage but more importantly, it keeps the bedding much fresher, reducing the number of times I have to clean it. My hamster also tends to look healthier and cleaner when the fans run, and he plays more.