The SR5521 from Vanlong is a SAW Resonator with Frequency 447.725 MHz, Centre Frequency 447.725 MHz, Insertion Loss 1.6 to 2.2 dB, Capacitance 1.6 to 2.2 pF, Voltage 30 V. Tags: Surface Mount, SAW Resonator. More details for SR5521 can be seen below.