Holley part number 13721NOS.
NOS/Nitrous Oxide System 13721NOS Nitrous Oxide Jet
Application Guide:
Super Powershot Precision SS™ Nitrous Flare Jet Package Of 6 Includes 1 Each Of Sizes 47, 53, 55, 61, 63, & 71 . NOS worked with experts in precision hole drilling to develop a proprietary manufacturing process for our new Precision SS™ jets during years of exhaustive research and development. The result significantly raises the bar in terms of jet accuracy and precision and renders all the competition's jets obsolete.