The Aeroflow brake combination proportioning valve simplifies the brake proportioning adjustments on vehicles with custom brake systems. It allows an easier mounting position right next to the brake master cylinder with the use of the bracket (AF300-149 Sold Separately) as well as less hard-line plumbing. This combination block maintains full isolation between front and rear fluid circuits in the tandem master cylinders. The rear circuit has a single inlet and single outlet with the adjustable proportioning valve. The front circuit has a single inlet with two outlets. It can be run as a single outlet with one outlet plugged, or used to split the plumbing on its way to the front brake calipers. Each inlet and outlet port accepts 3/16" brake lines with 3/8-24" inverted flare females. A cool feature of this unit is the built-in brake light switch. This brake light switch allows you to activate your tail lights with hydraulic pressure from your brake system.