This Device is for Airplane Modelers that have their Engines and Fuel Lines in "hard to get at" Places such as Cowlings. FEATURES: One-Piece Valve Assembly installed into Airplane with Convenient Fueling Probe for Refueling. INCLUDES: One Pre-Assembled Fueling Valve (Glow Fuel) One Fueling Probe (DUBP2339) One Knurled Nut w/Serrated Washer SPECS: Overall length (front to back): 13/16" (20mm) Mounting nut diameter (what is seen on outside of cowl): 1/4" Hole size (drilled through cowl): 3/8" Length inside cowling: 1/2" COMMENTS: Will require drilling 3/8" hole for acceptance of valve assembly. NOTE: This will ONLY work with Glow Fuel.