I really wish I had gotten this product sooner! At four months my son refused to have his arms swaddled. He immediately broke out or squirmed and whined until you let them out yourself. At five months old my son started turning on to his stomach in the middle of the night. At six months he would pull his blanket over his head which he managed to get loose because he was constantly rolling over from front to back and vice versa. This all caused me to start looking for a sleep sack since the only other one I had was too lightweight for winter. This is great because he will be able to grow into it.
There are buttons on the side because his arms are still too little for the entire arm hole. The zipper unzips from the bottom so that you don't have to remove the entire sleep sack if you want to do a diaper change in the middle of the night. It's very easy to get on because only one shoulder strap needs to be buttoned. The other side slips in like a shirt. The material is very soft and good quality.
The product also comes with a recommendation for what type of outfit your baby should wear depending on the temperature.
I highly recommend this product, even with the high price. It's worth the peace of mind and baby's safety most of all!