In a compact plastic housing has here a sponge and four colored pens including refill cartridge as a package together. Very handy to pack everything with a handle or store. The housing is indeed of relatively thin plastic, but nevertheless it is sufficiently stable. The pins fit comfortably in your hand and can be varied easily in the line width. The sponge works as it should. Manchesmal have to wipe more often, but that is rather on the pressure strength was written with. As a wrap-happy-package this set is highly recommended.
