My crate gave will fit up to 30lbs. I think they are considered medium size. They work for me. Kaleigh is a bit more crammed now that she is full grown, but when we travel she likes to ball up on her fleece blanket and does ok. They fit side by side in the back of my Mini-tightly. I like that they collapse easy.

And thanks SO much for updating this, it really is super helpful for people coming on here needing advice. I ordered the 30" one, so I think I'll be okay!