The mattress is well made and nice and firm.  Of course it fits perfectly in the crib it was intended for and makes for a nice small crib with a mattress with good support for growing babies.  There are no negatives about this product.  I wish it were 4" thick like the big crib mattresses for when my granddaughter gets older, but there is plenty of support and the portable crib that I bought it for has a sturdy bed support board beneath it which makes it firm for the baby.  Don't hesitate to buy this mattress ..it is very good.