The shipping experience was terrible, but that's on FedEx, not the seller. The actual mattresses (I ordered two for bunk beds) will do just fine. They are 5" thick instead of 6", FYI, but that's okay with me since they'll be used in bunk beds and the lower profile is what is needed. I'm a larger person (240lbs) and I laid on one to "test" it, expecting to really feel the springs at my weight, but they weren't even that noticeable/pokey. The mattress was comfy and both will definitely do just fine for a 4 and 5 year old. They are rolled up tightly/ compressed, boxes weren't heavy at all (maybe 25 lbs) .