We purchased a mini crib for use when our great granddaughter visits.  The bottom of the bed is quite firm and must not have been very comfortable as the baby didn't sleep well.   The first night she slept on the mattress she slept soundly and much longer than she did before we purchased the mattress.  She and we are looking forward to much better sleep as she seems to like it quite well.  Great quality and received quickly.  Would highly recommend.