I cut two sections of 3/4” EMT conduit as roof rack crossbars for my 2004 Jeep Grand Cherokee. When the sunroof was open while driving, the tubing made a loud, deep tone. My suspicion was bottle-blowing noises due to the open tube ends. I ordered the Maker Pipe tube ends and they arrived really fast for Fairbanks, Alaska! The tube ends fit securely with a small amount of overlap in the outside diameter. Alas, plugging the ends didn’t dampen the tone which now appears to be due to vibration of the crossbars in the wind. Nevertheless, the tube ends give my roof rack a finished look and keep water out. Thank you, Maker Pipe, for a fine product and excellent customer service!