Abstract: Blackboard rubber made of metal or having a metal base made up of two parts enclosed one within the other, the first part being in the form of a rectangular box and the second part being flat and forming a lid to the first part; the said second part comprises a centered metal plate and a magnet and is covered with a detachable rubbing sheet of soft material.

Abstract: A fastener which is affixed to a wall and on which a panel or other generally flat object is placed and held in position. The fastener has at least one straight and flat edge. The fastener is a device to be used at least in twos. On one fastener rests the panel and the other fastener holds the top of the panel to the wall. The fastener is made up of two interacting pieces (1, 2) of which one, for hanging (1), to be affixed to the wall and the other, for holding in position (2), which can be engaged by or released from the first to fix or release the panel. The first piece (1) has the general shape of an essentially straight angle piece of which one branch (1') is arranged in such a way as to enable it to be fixed to the wall, and the other branch (1") has an aperture (4) through which the second piece (2) can pass the second piece (2) is in the shape of a cross of which one part is longer than the other.

Abstract: A board intended to be used as a writing surface is provided with a frame and with a complementary border constituting one inseparable entity. The frame is continuous all around the periphery with a cross-section comprising three flanges. One flange is external to the other two, a second flange is equipped with a rim positioned behind the board and bearing against a foot formed on the complementary border, and the third flange bears against the front face of the board.