Trimmers, also known as variable capacitors, are adjustable electronic components that allow fine-tuning of capacitance within a circuit. They are designed for precise calibration and optimization of electrical parameters in applications where fixed capacitors cannot provide the required accuracy. Trimmers typically consist of a movable electrode or dielectric element that can be adjusted mechanically or electronically to vary the capacitance, often in the range of a few picofarads to several hundred picofarads, depending on the design.