When I first got my hedgie, I thought the "large" version would be big enough. Not even close. He quickly outgrew that. So the medium size is much too small. The biggest version available is the only one you should be using. If he's barely used the wheel, find out the store's exchange policy you got it from. They might allow you to exchange it for a more suitable one. Even if not, you still need to get a different one.Quilliam Is My Buddy said:Yeah, It's a medium-sized comfort wheel. I thought the XL one would be too big for his cage.
If you're using a sterilite bin, you can cut a rectangle in the top of the lid to accommodate the taller wheel size.
90 gallon is a little on the small side. You can connect another bin easily with PVC pipe. Then that way you can have an area for the wheel/exploring, as well as food/sleeping.