These indented design gas tanks are very smooth looking and enhance the lines of the High Neck Chopper frames. Available for frames with 4" or 6" down tube stretch and 3" minimum backbone stretch. The tunnel easily fits top tubes up to 2" diameter. Tanks come with weld-on mounting brackets, which are recessed in the bottom of the tank for that smooth hidden look. The rear of the tank is tapped 1/8"-27 NPT to take a fuel crossover line. To be used in combination with a 13/16" (22mm) petcock.