Hair Direct Ultra Hold Adhesive. For use with extended wear bonding only. This adhesive can easily provide up to 4 weeks of super-strength attachment. Ultra Hold isnt only the name, BUT also a great description of what you will get. Although its on the expensive side, anyone who has had problems getting a long-lasting bond using other adhesives will LOVE the strength and security offered by this product. It is also made from a waterproof, non-yellowing formula.