Antenna filters. One with cutoff at 35Mhz, one with cutoff at 85Mhz. Scan is 0-100Mhz, left is HF filter (ignore blip at 65Mhz), right is 80MHz filter. scan of filters responses: www.qsl.net/g4bxd/filter2.jpg Ideal for antenna's etc. Connectors are odd so best changed to 239 or such. £10 each. Ben.