Manthorpe Cross Flow Panel Vent - 600mm Rafter Centres (Box Of 50) The G625 Cross Flow Fly Screen Panel is designed for open eaves or cottage style situations and to provide a clear air passage between the roofs felt and loft insulation. The fly screen section consists of evenly punched slots specifically designed to prohibit entrance of large insects but wide enough not to be blocked by debris, paint or water droplets (seeBS5250 section 6) The G625 is suitable for 600mm rafter centres and where 25mm of airflow is required. 25,000mm/M Colour Black Material Lightweight Rigid PVC Manufacturing Process Vacuum Formed Free Airflow 25,000mm/M equivalent to a continuous gap of 25mm