The BW531 from Sainty-Tech Communications Limited is a 90 Degree Hybrid Coupler with Frequency 6 to 18 GHz, Average Power 27 dBm(IP1 dB), Insertion Loss 0.9 dB, Isolation 18 to 25 dB, Coupling 3 dB. Tags: Die. More details for BW531 can be seen below.