Peanut has been staying in a dog play pen exactly like the one in the in the picture.
The dimensions of the play pen are 3 feet tall and 4 feet across.
Peanut jumped out of it twice in the last two days.
Yesterday ; the first time she jumped out, I had a box with a lid (around 9 inches tall) inside her play pen. I took the box out.
Today , even without the box Peanut jumped out; also.
Now, the play pen has a cardboard ceiling fastened down with electrical wire.
My last rabbit, Bagel, (same size as Peanut) lived in the playpen for three years and never jumped out.
Peanut is one heck of a jumper.