5 INCHES-NOT THE 21. , So if I have any issues I will update the review. ) 3. "There are organized groups that wish to ban the phone book on account of its colossal waste of paper and resources. The box looked like it had been opened before. I liked that they require no installation, just set them on the pantry shelf, pushed them to the back, very sturdy, and slim enough that I can put items in front of them. Going to order another pair The headphones keeps on clipping in and out. 5 could get his foot into them. Also these have memory foam, which previous Acorns did not.