Sunny, the length of the tubes are such that about 4"s of the black tube is still inside the silver(emt) tube when the hatch is opened fully...when the hatch close the black tube slides into the silver tube...there is a pin hole in both tubes so that when pinned, it is a hard fixed length, not allowing the hatch to go up or down, staying securely in place regadless of wind action...We will have them powder coated and there will be an indicator ring on the black tube, so that when it shows, you will know that the pin holes are lined up...we came up with this because we were too broke and/or cheap to buy gas struts...should we decide to add gas struts later, the engineering is already done, just buy struts to match the length of our present setup and connect at the same points
madjack