MPR-D: This is a distance display unit that shows the distance to objects detected. It also contains the audible beeper.

This unit replaces the standard audible beeper unit.

Dash mounted / windscreen LCD distance display.

MPR-B: This optional unit contains an on/off switch so you can choose when you want the sensors to operate. Especially handy if these sensors are used on the front of a vehicle as the sensors can be turned off. They also contain a flashing display that changes the flash rate depending on the distance to a detected object.

This unit replaces the standard audible beeper unit.

 on/off switch with buzzer and flashing display