Proportioning valves are required for disc brake applications. The proportioning valve you need depends on your set-up. We offer proportioning valves in our kits, as well as sell them separately for all your needs.
USPS Priority shipping Flat $12 on these listed proportioning valves
PV-2 PV-2 diagram pdf
PV-4 PV-4 diagram pdf
PVC-B (adjustable and the only one we recommend) PVC-B diagram pdf $80
(diagram for informational and reference use only)