Have the packet received today. Unfortunately, there appears to have been damaged in transit for which the seller of course nothing can. Apart from that, however, the color is applied very unclean, in some places they already dissolves, forming cracks or got a rough surface. Seems to hang together with the material from which the box is made. At the damaged site, it looks like heavily pressed cardboard.
I am assuming that there is therefore something quick whistle from the surface at every little bump. If you probably carefully deal with the box and you're lucky during transport they would but serve their purpose