Fits standard Babies R Us brand pack n play perfectly. Great mix of foam, firmness, cushion and plastic. My babygirl is loving it right now! Carters pack n play sheet fits. I wanted something slightly more comfortable vs. firm as my little one is 6 months old and was starting to hate sleeping on harder surfaces...She fell right asleep. Only reason I didnt rate 5 stars is because I was hoping it was a tad more soft (pillow topfoam like). Still a great product.