The U90 from Johanson Technology is a RF Capacitor with Capacitance 2.7 to 4000 pF, Dielectric Constant (K) 23 to 12000, Dielectric Strength 2.5 x WVDC, Voltage (WVDC) 100 V. Tags: High Q Capacitors, Ceramic Capacitors. More details for U90 can be seen below.