I have for sale an Icom Fl100 500hz CW filter that fits many Icom radios, including the 706 series, 725, 726, 728, 729, 735, 736, 737, 738, 746, 756, 761, 765, 775, 781. It will not work in the 703, 707, or 718 models. Makes these radios perform much better on CW. I am asking $65 shipped for it and can take paypal/check/MO. 73 John AF5CC