This foam fills up the entire top of the bed.  No skimping on the size.  it seems very comfortable so far, but I've only used it for a week now.  It did have a foam smell when it came and I was skeptical it would air out, but I left it open on the floor in my guest room for 2 weeks and it is fine!!  They did say to air it out for a couple of days.  I'm glad it actually lost the smell.  I'm pleased with this product. 

Pros: Fills entire bed, very comfortable. 
Cons: It does need to air out, but that is normal with foam products.