Parametric equalizers typically use knobs and sometimes buttons. Controls such as knobs, switches, and pedals can be used to send these messages. The least-cleaned objects were bathroom light switches, room door knobs, and bed pan cleaners. Electric guitars have magnetic pickups, volume control knobs and an output jack. The interior was given sportier gauges with better backlighting and higher quality trim and knobs. The system came pre-wired on a custom 11-hole white pearl pickguard with white knobs. This guitar was heavily modified with stickers, hardware and tone control knobs. These use Rajay turbochargers with manual wastegates operated by twin knobs under the throttle quadrant. It was like aluminum boxes, little knobs sticking out, and patch cords. The separate seatbelts warning buzzer between the wipers and lights knobs was discontinued. Their heavy skulls were ornamented with multiple knobs and ridges. The bow was often decorated with moulded knobs or spikes. Turning both knobs simultaneously makes diagonal lines. Each function table had 728 rotating knobs. Ceramic cleats, which were block-shaped pieces, served a purpose similar to that of the knobs.