Network Sciences manufactures standard and custom-designed crystal and LC filters, and crystal discriminators.
Specific products are passive band pass, band reject, low pass, and high pass filters from 1KHz to 2.5GHz, including:
Discrete crystal filters from 100KHz to 300MHz
Monolithic crystal filters from 10MHz to 110MHz
LC filters from 3KHz to 2.5GHz
Crystal-based disciminators, 5MHz to 80MHz