It's the tried-and-true jewelers hard soldering flux. Yellow-green and self pickling, it's the best in water based fluxes. Well-mixed to eliminate suspension.
This deoxidizing flux keeps metal clean during melting and pouring.
This is a hot and handy item for depositing flux or any other liquid exactly where you want it with just an easy squeeze.
Four ounce spray bottles sold in a packs of three. Use to spray liquid flux.