A flexible, purpose-made adhesive for speaker cone and surround repair — the kind of glue that stays slightly flexible after curing instead of drying rigid and brittle, which matters when you're reattaching a torn foam or cloth surround, sealing a cracked cone, or re-gluing a voice coil former.
A rigid adhesive (like standard super glue or epoxy) will crack again under the first big bass hit; this is formulated to move with the speaker instead of fighting it. Essential for anyone doing their own speaker refoaming or cone repair rather than sending cabinets out to a specialist.
