The Fuel Nipple (Pressure Fitting) Screws Into the Muffler, and Provides a Place to Connect Fuel Tubing Onto the Muffler. The Fuel Tubing Will Then Run Back to the Fuel Tank. This Setup Will Cause the Fuel Tank to Become Pressurized, Which Helps To Keep A Constant Flow of Fuel to the Engine. INCLUDES: One Fuel Nipple (Pressure Fitting) One Red Washer REQUIRES: MUFFLER SPECS: Length:14.14mm (.557") Thread Pitch: .5mm, 3mm diameter Inside Hole Diameter: 1.40mm (.055") Fuel Tubing Size: USE A TUBING WITH 3/32" INSIDE DIAMETER. ir/JL Updated 5/4/05 JCT