The CAP CER 3900PF 250V C0G/NP0 1210 is a type of ceramic capacitor. It has a capacitance value of 3900 pF and operates within a voltage range of ±10% at 250V DC. This component falls under the C0G or NP0 classification, which denotes its temperature-stable characteristics. The 1210 designation refers to the component's metric case size of 3.2mm x 1.25mm (or 3225 in imperial measurements).