Hint: before doing any drilling, unpack all the parts. We did order a small, but this was very very small. These slippers are just ok. You cannot hear any outside noise! I bought a pair of Chacos on vacation in a tennis shoe style and I love them. I have not walked far in them yet . There is only an SD card slot. It was sample and easy to assemble without any tool needed, I might only spend 30 minutes less to get it done. no sound. But the rack is heavy even when its empty.