A swaddler is a blanket made with “wings,” pockets and/or other shapes, as well as snaps, hook and loop fasteners, zippers, or other fastener to make swaddling easier for parents and to keep little Houdini’s contained in their swaddle.

also called: baby wrap, infant wrap

The ergobaby swaddler has been recommended:

http://store.ergobaby.com/swaddlers#instructional-videos