https://www.moonraker.eu/icom-fl-431-3khz-high-spec-first-if-roofing-filter?___store=english2559Icom FL-431 3kHz - IF filter for HF/6M band filter https://www.moonraker.eu/media/catalog/product/f/l/fl-431_500x623.jpg59.9959.99GBPInStock/Amateur Radio Equipment/Amateur Radio Equipment/Other Accessories/Amateur Radio Equipment/Other Accessories/Internal Boards (Filters, Crystal Units etc)