20k ohm resistor written as 203 in code; potentiometer, trimmer, side-adjust.

Adjusted with a screwdriver.

Resistive Material: Metal, Plastic
Body Size (Approx.): 7 x 6.5 x 4mm / 0.28" x 0.26" x 0.16"(L*W*T)
Pin Size (Each): 5 x 0.7mm / 0.2"x 0.03" (L*Tip Width)
Color: White, Blue, Silver Tone

A potentiometer is a variable resistor with 3 pins, as shown in the picture.