The CAP CER 3900PF 100V X7R 1808 is a type of ceramic capacitor. It has a capacitance value of 3900 pF and operates at a voltage rating of 100V, with a tolerance of ±20%. The capacitor conforms to the X7R dielectric, which provides stable temperature characteristics, making it suitable for various applications. Its metric designation is 1808 (4520 in metric units).