A device, such as a set-top box, may include logic to allow television customers to automatically test and adjust the quality of the displayed video signal. The gripper includes multiple fingers arranged around an axis, an elastic finger mount, and an actuator mechanism structured and arranged to move the fingers to selectively grip or release the sample. To overcome the drawbacks and problems the prior art one aspect of the present invention is directed to a metallic tower comprising lattice members with a channel section, wherein the length of the channel web is smaller than the length of the channel legs. The air inlet device allows hot air to be diverted to the side of the deflecting rollers facing away from the process chamber such that hot air flows over the respective deflecting roller and the fibers before it enters the process chamber.