A rare and hard to find item: This is the narrow band crystal filter, used by Watkins-Johnson in 8607 Minicepter series, flat and thin with wire leads for surface mount, 21.4 MHz C.F. 300 kHz bandwidth.     WJ P/N 92777A.  Price is for one. This is more desirable for listening to FM radio, and may be harder to find, as most minicepters were rigged for wider bandwidth UHF interception work (Many start at 500 kHz and go up in bandwidth).