This AP CP3550-13 brake proportioning valve provides you with 7 distinct settings from which you can set up the balance you require with front to rear braking. 
General installation information
To obtain the best performance using this valves, the brake balance should be biased towards the rear so that with the valve piped in to the rear line and set in position 7 where virtually no reductions occurs, the balance is as much to the rear as will ever be needed. Moving the control lever to a lower setting will progressively reduce the rear line pressure giving more bias to the front, for use when more grip is available.