Kel Tec RFB Quad Rail And Riser Combo Black. Two scalloped cut-outs on the top of the Picatinny allow the shooter freedom to adjust the gas system if needed and allow the ejected casings to leave the ejection port. Take caution on which accessories to mount on the left hand side of the weapon since this could block the ejection port. Riser is made out of hard coat anodized 6061-T6 aluminum. Kit comes with one (1) RFB-420-Quad Rail one (1) Locking Nut and wrench one (1) set screw with hex key. Black. Specifications for Kel Tec RFB Quad Rail And Riser Combo Black RFB-425: Mfg Item Num: RFB-425 Type: RAILS_RAIL_KITS_GA Master Model Header: RFB Quad Rail And Riser Combo The Kel Tec RFB Quad Rail And Riser Combo Black RFB-425 is a quality addition to the Kel-Tec lineup. For more great deals on Gun Parts by Kel-Tec please browse our Kel Tec Gun Parts page.