mechanical device small, round shape a raised center a metal or plastic surface a narrow shaft extending from the center a hole in the center of the shaft to accept a screw or other fastener a handle or other elements to allow for manual manipulation
knob which has mechanical device knob which has small, round shape knob which is a raised center knob which is a metal or plastic surface knob which is a narrow shaft extending from the center knob which is a hole in the center of the shaft to accept a screw or other fastener knob which is a handle or other elements to allow for manual manipulation