Amy, I'm a novice to gerbil keeping (ie, take what I say with a grain of salt), but I would think a metal elbow pipe would be fine. I have several pieces of sch.40 pvc 2" pipe fittings in my cage and the gerbils love them. They are able to gnaw the plastic, but sch.40 is so thick I think they will last a long time. And they're generally cheaper than metal fittings. (Schedule 40 pvc fittings are made of heavy plastic; schedule 30 fittings are thinner and probably much less durable with gerbils.) My 2 cents. -Jeremy
