The part number is CAP CER 3.9PF 100V C0G/NP0 1206. It is a ceramic capacitor with the following specifications: capacitance of 3.9 pF, tolerance of ±0.5pF, and voltage rating of 100V. The ceramic material used is C0G/NP0 (1B), and it has a metric case size of 3216 equivalent to the standard 1206 package.