Depends on the size of the snake. My 420g girl seems to really love her large RBI hides. She sits on top of them at night and goes inside during the day. She also digs little tunnels under the aspen and makes her own "secret" ways into the hides
I have a young 140g female that squeezes snuggly into the small hides. Two of them are perfect for a 10gallon aquarium for baby snakes. I have a couple medium hides that will go into my new bigger cage that she'll move into in a couple weeks.