Windows from Comar Architectural Aluminium Systems have exceeded the requirements of the BS 6375 Part 1:1989 Classification for Weather Tightness. The test sequence on the company's 5 Pi Reversible Pivot Window determined tightness in respect to air permeability, water penetration and wind resistance. It achieved air permeability of 4.54 (m?/hr/linear m) at air pressures of 600 Pa, well below the permissible level of 6.65.