A rug of this type appears exactly the same as a carpet of flying, and it performs the functions of one (6-ft x 9-ft size), but a rug of welcome has other powers in addition. 

Upon command it will function as a rug of smothering, entrapping any creature up to ogre-size which steps upon it. 

A rug of welcome will also elongate itself and stiffen to become as hard and strong as steel, the maximum length being 27-ft long at 2-ft width, to serve as a bridge, barricade, etc. 

In this latter form it is AC 0 and will take 100 hit points to destroy. 

Best of all, the possessor need only utter a word of command, and the rug will shrink to 1/12 size for easy storage and transportation.