We sell several filter kits to suit our X1M PRO HF QRP Radio.
Band-Pass-Filters (BPF), either single or double bands for:
Low Pass Filter (LPF) for 10m
These filters are required if you 'unlock' the X1M PRO radio to transmit on these WARC bands. Without these filters, each of these bands is only filtered by a 10m LPF and therefor has high undesirable spurious emmissions.
We also have Audio filters to use inline with headphones/ext speaker to deal with QRM/QRN on HF - (Now in stock)