- Rytons A1® Fire-rated Range - Fire-safe ventilation for multi-storey buildings The Rytons A1® Fire-rated Range is the UK's most comprehensive collection of A1 classified, non-combustible HVAC ducting kits, air bricks, cavity weep hole ducts, external weather louvres, cavity liners and compartment ducts. With hundreds of fully customisable lines available, it's easy to find products [...]