Top Clamps are used to close off the dustproof wall or dustproof door at ceiling height. The Top Clamp can be placed on the upper pole of the following supports:  QS30, QS60 or QS70. The spring mechanism pushes the plastic curtain over a length of 30 inches (75 cm) against the ceiling. It is possible to place 2 Top Clamps on one support, even when the support is turned more than 90 degrees! Patented!