The Imse Vimse Bumpy® Soft Cover is soft, breathable, and very adjustable.  It has a polyurethane laminate inner and polyester knit outer.  Keeps baby dry, but still allows air circulation.  The newborn size is nice because it fits up to 13 pounds, which is several pounds more than most other newborn covers. This is the new version with reinforced velcro edges and improved design.

Available in five sizes: 

Newborn(6.5-13lbs.), Small (11-17 lbs.), Medium (15-22lbs.), Large (20-26lbs.), X-Large (24-30.5lbs.)