Salon Pro Hair Bonding Glue is a latex-based adhesive formulated for attaching wefted hair extensions and wigs to natural hair, sold under Salon Pro's "Anti-Fungus" branding. It's designed to be applied to the stitched (weft) side of the extension rather than to the scalp -- the weft is glued and then pressed against a parted section of natural hair to bond.
The formula's base ingredient is natural rubber latex, so it carries a latex-allergy warning; it should never be applied to the scalp, skin, or near the eyes, and a bonded piece isn't meant to be pulled apart when removed, since that risks pulling out natural hair. A dedicated adhesive remover, rather than water or shampoo alone, is used to dissolve the bond.