This is a 3900PF 50V C0G/NP0 ceramic capacitor with a tolerance of ±10 and a voltage rating of 50V. It measures 1812 in metric size or 4.3 x 2.8 mm, making it suitable for various electronic applications, including those requiring precise capacitance values like the CAP CER 3900PF 50V C0G/NP0 (1B) series.