The only inside-out, leave-in hair repair treatment that both reverses and fights future damage, reinforces hair’s strength, and reduces breakage with our highest concentration of reparative Alpha Keratin 60ku®. Repairs | Mends | Strengthens Damage Reverse™ Serum revolutionizes hair repair by not only fighting future damage but by instantly repairing damage. Packed with the highest percentage of our hair-identical protein, Alpha Keratin 60ku®, this wonder-working miracle serum instantly repairs the severed bonds that give hair its strength, naturally restores damaged peptides to give hair elasticity, and refills each strand with keratin to smooth, soften, and protect from future harm.