Abstract: A frame for silk-screen printing holding a cloth of thermoplastic material attached to a thermoplastic frame surface is disclosed. The frame elements comprise a rectangular metal frame with each element having a metal bar with outwardly directed flanges attached to it. A series of contoured plastic strips having channels engage each of the flanges and are slidably mounted on each bar. The cloth is stretched across the contoured plastic strips and by the application of heat the strips melt and fuse with the cloth.

Abstract: An electric switch arrangement for use as a current supply switching means for a bipolar electric load is disclosed, comprising two switches connected in series with each other and with the load and located on opposite sides of the load. A monitoring equipment is provided for supervising the operation and function of said switches. Said monitoring equipment comprises potential generating means which are arranged, when both said switches are open, to generate at each pole of the load a potential deviating from the potential existing at said pole when anyone of said switches is closed or both said switches are closed, and sensing means which are arranged to sense the potential of at least one of the poles of the load.