The CER0391A from CTS Electronic Components is a RF Duplexer with Frequency 1.76 to 1.88 GHz, Band 1 1.85 to 1.88 GHz, Band 2 1.76 to 1.79 GHz, Power 3 W, Insertion Loss 2 dB. Tags: Ceramic, Surface Mount. More details for CER0391A can be seen below.