Aeroflow 2-1/2" Billet Aluminium Weld-On Filler with Polished Cap (AF460-40P)2 1 2" ALUM WELD BUNG AND CAP Part Number: AF460 40P Billet Alloy Weld On Filler & Cap. Aeroflow Performance non vented filler caps are manufactured from 6061 T6 aluminium and are supplied with BUNA N (wide range of fuel and oils) and EPR (Nitro methane fuel O Ring seals. Available in 1", 1 1 2", 2", 2 1 2" & 3" diameters in Blue, Red, Black,Gold, Purple, Raw, Polished and Silver anodized finishes. Bore Size: 63. 5mm (2 1 2") Neck O. D.: 76. 2mm (3")