The KFF6637C from CTS Electronic Components is a RF Duplexer with Frequency 1.85 to 1.99 GHz, Band 1 1.93 to 1.99 GHz, Band 2 1.85 to 1.91 GHz, Insertion Loss 3.9 to 4.6 dB, Attenuation 37 to 59 dB. Tags: Ceramic, Surface Mount. More details for KFF6637C can be seen below.