This product worked well in slowing down our drawers to close. I followed other posters advice on installing these gears. I also added another piece of wood to prevent the drawer from popping out of the slide out mechanism (you can see it in the picture). Generally we only needed one per box. Even heavy boxes, one worked fine. If you use two I find that they are too difficult to open. The only thing I would change when designing these parts is to have a spring tension screw adjustment inside so you can adjust how much force is required to open/close the drawer. The payoff for these details is high, but I would classify this as a mid-range project depending on your style of furniture.