The fabrics are fleece, with interlock for the collar, waistband and cuffs. I also underlined the sleeves with tricot to make them nice and slippery so the jacket would be easy to take on and off. The tricot adds some wind resistance too, so that's a nice bonus.
I made a size 4. and it is a perfect fit, but there is definitely no grow room. Fortunately, it'll be easy enough to whip up another once he outgrows this one. I do love the way the waistband holds the jacket snug at the waist. Very cozy!
It is nice and comfy for play, and he can do the snaps himself, which is really nice. I used red capped snaps from SewBaby.
It even kept him cozy in the rain! And don't let that forlorn look fool you. He threw an unholy fit when we made him come inside.