Glidevale AV50 Abutment Ventilation Unleaded has been designed to provide an unobtrusive solution for high level ventilation to roof spaces. It can be used at the top abutment of a pitched lean-to roof, which is especially useful where there is a limited height above the pitch, due to windows. It can also be used in conjunction with traditional ‘lead roll’ ridge details on plain tile and slate roofs.