Engineering Dictionary of Capacitor Terms
"A",
"B/C",
"D",
"E",
"F",
"G",
"I/L",
"M/N/O",
"P",
"Q/R",
"S",
"T",
"V/Z"
Variable Capacitor: An adjustable Capacitor. A capacitor that does not have a fixed value. A trimmer capacitor is also a variable capacitor but only used when small or subtle changes are required. The physical size of these trimmer capacitors are also small and require a flat-head screw driver to make adjustments.
Panel Mount Trimmer Capacitor
Through hole parts are used as examples, but surface mount components are also possible. Ease of use is not necessarily a consideration when you also consider things like cost, size and the number of times the device will be used. Again the trimmer is only meant to be a minor adjustment, and many times an adjustment that might only be made once.
3-Terminal Trimmer Capacitor
Through Hole Trimmer Capacitor