quote: "cog/precision multileyer capacitor.very small. "
COG, or more correctly C0G (C zero G) is just a type of ceramic material. It is the same as NP0. The tempco of capacitance when used in a capacitor is close to zero (spec'd at +/- 30ppm/degree C I believe). They have very low dielectric loss and dielectric absorption and are non-microphonic if made right. They will tolerate high and low temperatures too.
The disadvantage is low volumetric efficiency for easy-to-make thicknesses of material. So single layer parts are in the low tens of picofarad range typically, and anything above that region is multilayer. They get expensive and typically bulky in higher C values. I have a few samples of a 0.1uF C0G 100V part that Thomson made for a while but then discontinued. These days I think the stocked values run to about 2.2nF.
When you have very deep pockets you can get them made custom, about as big as you like. I think it was AVX that did one for the International Space Station. Very low inductance and loss, 270uF (!!) iirc. Probably a >$100k capacitor.
As Sun Ra says, Space is the Place...
