The CER0439A from CTS Electronic Components is a RF Duplexer with Frequency 3.45 to 3.6 GHz, Band 1 3.55 to 3.6 GHz, Band 2 3.45 to 3.5 GHz, Power 2 to 20 W, Insertion Loss 3 dB. Tags: Ceramic, Surface Mount. More details for CER0439A can be seen below.