You know, the one that is pretty low, and has a tent you can buy separately. We are thinking of getting it for Dora. My first question is, can you use a regular twin mattress with it, or does it have to be an Ikea mattress? Second question, has anyone every put a toddler bed or mattress under it? Right now Arwyn sleeps in a huge crib/toddlerbed with attached dresser, and it takes up so much room. I'm thinking it's not the greatest use of space, because we are moving Laurel in with them. OTOH, I don't want to use a regular bunkbed because they are much higher and I have safety concerns. So my thought was to just put Arwyn's crib mattress on the floor under the loft bed. That way I could easily pull it out to vacuum the carpet. Or if I really wanted her off the floor I could get a cheap toddler bed. Then we'd have room for Laurel's crib or a pnp, which is what she uses now when she sleeps with them.