FibreMetal F4001 Cup Sessions are one of the welding helmet protective cap components second to the F4002 to make up the Model 4000 QuickLok mounting system Fully adjustable to better fit FibreMetal caps and major competitive Brands, the welding helmet adapter kit provides more permanent mounting for longer term or high activity applications The F4001 Cup Sessions fit over the F4002 base and includes the pivot points for the attachments of the user's choice•Cup session•Part of F4000 Quick-Lok Complete Kit•Fully adjustable•Provides more permanent mounting.