This is a transparent plastic exercise wheel, made by GEX, and is 21cm in size. I used it for about two months for my Campbell's hamster, but I'm selling it because my hamster has grown and I've upgraded the wheel size. There are some minor scratches, but it's still usable. It's perfect for Djungarian hamsters, etc. - Brand: GEX - Type: Exercise wheel - Color: Transparent/White - Material: Plastic Thank you for looking.