Water tightness requires a high level of technical expertise. It is expressed by the letters npd (when no performance has been determined) or by a number from 1 up to 9 followed by a letter (A – unshielded and B – shielded). To understand the importance of this parameter, one must consider that in order to reach the lower class 1 (A or B), the product must prevent the passage of any drop of water for at least 15 minutes. Higher classes are achieved by retaining water tightness at ever increasing test pressures. When exposure to the elements is especially severe, our Sigillo tightness kit provides a water tightness level class 7A, equivalent a 300 Pa test pressure under fully exposed unshielded test methodology, on the Grand Superior, Elite and Superior doorset models.