Medium is very large, great for a Syrian!
I was actually shocked how big the medium is! Luckily I have a 100cm x 80 cage, so plenty of room for it. If you have a standard size pet store bought hamster cage, then the medium will be way too large for most standard hamster cages. To give you an idea, it's the length of my forearm, and around the width of a DVD case. My little Russian dwarf has been enjoying herself, in and out, climbing on it, plus it has a hole on top, so she has come out through there too Excellent size for hamsters/Rats