The choice of a system for Agile One lifting doors depends on the height and the weight of the furniture door. To do so, you simply need to follow these simple steps: 1. Check the height and weight of the furniture door. 2. Once you have obtained the values you need to calculate the strength of the spring, S = H * (W + 2 * Wh), in terms of: H = Height of the door in mm. W = Weight of the door in kg. Wh = Weight of the handle in kg. You can choose the lifting system according to what interval the strength of spring S falls under. The MEDIUM interval is between 500 and 1,500, HIGH between 960 and 2,350. For example, we have a door with a height of 400 mm and a weight of 5 kg, with a handle that weighs 0.22 kg. The strength of the spring would be S = 200 * (5 + 2 * 0.22) = 1,088. Therefore, we would choose the HIGH strength range because it is in the interval of 960 and 2,350.