Abstract: A natural air cooled rack for vertically disposed printed boards. The rack comprises a plurality of stacked cases for housing printed boards. Each of the cases has draft openings on the upper surface and the lower surface thereof. An interspace is formed between one or more upper cases and the one or more lower cases. At least one supply opening and at least one exhaust opening are formed in the front portion of said interspace. The supply opening communicates with said draft opening on the lower surface of said upper case while said exhaust opening communicates with said draft opening on the upper surface of said lower case. Said exhaust opening is located substantially above said supply opening.

Abstract: An electronic device comprising a printed circuit board unit contained in a protective cover, and which also serves as a guide member when the electronic device is inserted into a mounting chassis. The cover is constructed from a member formed in one piece, the member having cover portions and flexible hinge portions for permitting the cover portions to be pivotally moved with respect to each other between open and closed positions of the cover. The printed circuit board unit has a printed circuit board which is integrally formed at respective opposed ends with an electrical connector and a handle, which both project out of the cover. Such construction is simple and inexpensive to manufacture.