The CAP CER 3900PF 100V X7R 1206 is a specific type of ceramic capacitor. It has a capacitance value of 3900 picofarads, operates at a voltage rating of 100 volts, and belongs to the X7R category. This category signifies that the dielectric properties change in response to temperature variations. The physical dimensions are 1206 (also referred to as 3216 in metric measurements), indicating its size.