This is the first time I use spacers. When I first got the posts, I could barely push the posts into the closed position with my hands. Luckily I found that opening/closing shelves with hands is not a good test. I've used them for: 1) I installed these gas struts on a bench seat with a drawer underneath. The seat weighed about 20 pounds and a brace was enough to hold the seat open. 2) I also installed one of the designs on the top storage door that opens. The drawer door is solid wood (24" x 13" x 0.5"). The door opens vertically to the ceiling. One design was enough to keep the cabinet in place. In the future, I might install a second one on the other sides of the door to keep the door from rocking Overall very good material and I expect these designs will last a while.