The screen material is wound on a spring loaded spindle contained in a housing tube. The upper screen edge is fitted to a reinforcing bar. The spindle has an end cap on one side with an externally threaded sleeve. This is fixed to the spindle by a pin passing radially through the spindle. The head of the pin projects. A nut is fitted to the sleeve and prevented from rotation by a projection sliding in a tube slot. As the screen is extracted the nut moves axially. when the side of the nut and the pin head contact, the spindle is stopped and the screen can be tensioned by telescopic adjustment of the support column. The design is simple, compact and cost saving.
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