"L Series" Repair Kits for Marquest Lab Fixtures & Throttle Master Needle Valves The Ultimate in On/Off Product Cycle Life *Offers all new PTFE Sealing with Unlimited Life Warranty. PTFE on/off seal is easily replaced in the field, no tools required. Exceptional low torque on/off operation Parts List: L Series PTFE Tipped Needle, Threaded Insert, Bonnet"Cap", Handle, Color I.D. Ring