Precision Reflex PRI Delta Replacement Bottom Rail Forearms 5.5in Black. The PRI 3 '' aluminum forearm rail for M-LOK slots is hard coat anodized black. The rail sections weighs 1.2 Ounces is 3.25'' total length and comes with hardware to install. Specifications for Precision Reflex PRI Delta Replacement Bottom Rail Forearms: Manufacturer: Precision Reflex Color: Black Fabric/Material: Aluminum Cant: 0 MOA Gun Make: AR Platform Condition: New Package Contents: Precision Reflex PRI Delta Replacement Bottom Rail Forearms Precision Reflex 05-071-5B: PRI Delta Replacement Bottom Rail Forearms 5.5in Black