The FRTCB is a powder-coated tank vent cap. The cast iron base is manufactured to fit all 2\" NPT tank openings and includes padlock security feature. Vent cap acts as a physical barrier to ambient environment reducing evaporation of fuel due to temperature changes. Prevents pressure from building up in tank and releases vacuum allowing for consistent pump performance despite environmental conditions. Prevents contaminates like dirt rust and water from entering your fuel supply ultimately maintaining fuel quality and protecting your equipment. Threaded tank base is finished with a powder coating providing long term corrosion resistance and lifetime performance. Comes complete with a padlock compatible threaded base protecting your fuel inventory from theft and fraud.