A blank 44 for a sleeve type casing 46 with a detachable cover flap 58 for receiving a recording medium is formed by punching and folding along lines formed in it, and has a U-shaped notched portion 62 for finger gripping of the contents of the casing at an edge of the mouth 92 of the casing 46, wherein the cover flap 58 has an insertion flap 60 and a line of perforation 84 so that the cover flap 58 and insertion flap 60 can be detached, leaving a second edge with a U-shaped notch portion 78. The blank may be of plastics sheet material. <IMAGE>
