Approx sizes are on the first message/post. They're all handmade with unique shapes. The entrance and holes are not oval shaped because I have tweaked them a bit and they're flattened at the bottom of entrance and plecos are quite happy with this as they're same shaped.
There is only one way in as the top hole is only a fake.
To picture it out my brown Ancistrus sp. male which is about 4' is getting to a smallest one. I don't know why he is picking it, but it looks funny when he is trying to squeeze into.