The CER0277A from CTS Electronic Components is a RF Duplexer with Frequency 3.4 to 3.55 GHz, Band 1 3.5 to 3.55 GHz, Band 2 3.4 to 3.45 GHz, Insertion Loss 3.4 dB, Operating temperature -30 to 80 Degree C. Tags: Ceramic, Surface Mount. More details for CER0277A can be seen below.