I checked those out. My largest door only weighs 17lbs and even the smallest automobile strut that I could find was too powerful. There's some math there that I can't get my head around to try to find the appropriate strut and locate it in the correct position on the door.
What about the thing used on screen doors? you slide the little do-hickey in place and it stays....
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I once had a Big tank...I now have two Huskies and a coyote