Allan Brothers' 'H' type window has been tested independently to BS 6375 Part 1 and has achieved the following ratings:
| Air permeability | 600Pa |
| Water Tightness | 300Pa |
| Wind Resistance | 3,000Pa |
Allan Brothers' 'H' type window has been tested independently to BS 6375 Part 1 and has achieved the following ratings:
| Air permeability | 600Pa |
| Water Tightness | 300Pa |
| Wind Resistance | 3,000Pa |
