fash n kolor Baby Doll Crib Set with Pack n Play Bassinet Blanket & Carry Bag for Baby Doll | Baby Doll Crib Set for Kids

Will it fit the baby alive dolls?

How do you lock the top rails in place?

I purchased this for Grand daughter almost a year ago. It is a little saggy in the bottom center now. Is there a way to tighten it up?

One description says up to 20 inch dolls and another says 18 inch. Which is it?