Both have the same functions, but you can choose to use a wall-mount or belt opener if your preference is quieter. Although chain drives last longer than belts they are more noisy. Although screw-drive motors can be used to open doors, they are not as silent as those powered by belts. A DC motor, which is more expensive but increasingly popular, is also quieter than an AC motor. Nylon rollers equipped with ball bearing axles are quieter than those made of steel.