A strip of fastener material adapted for securing to the surface of a foam bun during molding, carries on a first surface an area of outwardly extending fastening elements constituting one half of a touch fastening system. The first surface is arranged to be positioned so that it faces into a trough in a mold wall and this first surface is provided with a pair of elongated flexible sealing lips adjacent the edges of the are. Magnetizable means are also carried by the strip and the fastener strip has portions extending laterally beyond the sealing lips and beyond the edges of the trough in the mold wall. A strip of removable pressure sensitive tape covers the surface of the fastening elements and extends completely between the lips.