This is a 18pF ceramic capacitor, specifically the CAP CER 18PF 50V C0G/NP0 1206 model. It has a capacitance value of 18 picoFarads, operates at a voltage rating of 50 volts, and adheres to the C0G/NP0 specification. The component is in the 1206 (3216 Metric) package size.