The CER0438A 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, Power 2 to 20 W, Insertion Loss 3 dB. Tags: Ceramic, Surface Mount. More details for CER0438A can be seen below.