KB500A18AL is a solid aluminum control knob featuring a straight knurl design with a line indicator positioned on top. The knob is constructed from machined aluminum and is available in natural or black anodized finish, providing both durability and aesthetic appeal. It accommodates 1/8" and 1/4" diameter shafts with positive retention using #6-32 set screws (typically one or two supplied depending on configuration). The knob measures 0.500 inches (12.7 mm) in diameter with a height of 0.430 inches (10.9 mm), making it compact and suitable for space-constrained applications. This knob is ideal for laboratory instruments, industrial control panels, audio equipment, and precision measurement devices where reliable shaft engagement and clear position indication are essential.