brushed metal knob -

adjustment alignment alligation alloy arm arrangement ball brass brassy bright brilliant bronze brown brushed burnished button caster castor circle circular composition control cool copper cuprum disk faceted fusion gear globe glossy grasp grip haft handgrip handle hilt holder iron ironwork key knob lever machine machinery manubrium mechanism metal metallic metalline moony orbicular pen pin polished readjustment red regulation roller rotund round shaft shining shiny snap stick tack tiller tin-pan trundle tuning vector wheel