What made me choose this model: no "round" (or button) but a sober upholstery vertical rectangles (18 x 25 cm). Be careful down there a black band, so do not take broader than the bed because it would be! (For my bed 140 is beyond the sides do than 4 cm). There are also holes for possible fixing down bolts (8 holes) but the screws are not provided. This is not necessary, however, the bed is sufficient to press the object against the wall.
PS: Good price too! (189 EUR)