Having a hard time finding a Power Tube for your vintage Nelson based marker? Grab one of our new Stainless Steel 0.180 ID (approximately a 5.6 or a 5/6 size) Power Tubes which come as a package with a Valve Cup, Valve Seal and Power Tube. These are a replacement for a Lapco/Taso/Line SI/ICD/Nelson/etc power tube. Made in the USA.