NOS NOS is making available replacement siphon tubes for its most popular nitrous bottles. We offer the siphon tubes for 5 lb all the way up to 20 lb bottles. These 3/8" I.D. tubes are made from 6061 aluminum and can be used on any NOS Hi-Flo or Super Hi-Flo bottle valve. This screw-on siphon tube can be used as an upgrade for an older style compression fitting tube.