How does a brake bias adjuster work?

how does a brake bias adjuster work?what are all the parts involved in the system?how can i replicate it as i need to do it for my project...any links or stuff that can be oh help are welcome..|||Gives you the ability to adjust the brake pressure from front to rear. Works by resticting fluid to front or rear brakes. You could get a brass junction block at a hardware store and drill holes into the passages and use bolts to get an adjustable restriction of the fluid.