The part number CAP CER 30PF 3KV NP0 1812 refers to a specific type of ceramic capacitor. This component has a capacitance value of 30 pF and is rated for operation at voltages up to 3000V (or 3kV). The 'C0G' designation indicates that it belongs to the C0G/NP0 class, which is characterized by its stable temperature characteristics over a wide range. The '1812' or '4532 Metric' dimensions specify the component's physical size.