TIGI S Factor Wonderful Tonight Overnight Treatment 3.4oz For Damaged, Dry and Depleted Hair in Need of Intense Repair. This vegetable derived, multi-functional strengthening complex helps rebuild hair strength and repairing damage. S-Factor Wonderful Tonight improves hair's resistance to breakage and is proven to triple the strength of damaged hair. This overnight treatment is infused with Keravis to penetrate the cortex and strengthen the hair while also creating a protective barrier that lubricates and reinforces the cuticle. Hair treated with Keravis was shown to have a higher fatigue lifetime, making hair more resistant to breakage. Tigi S-Factor Wonderful Tonight Overnight Treatment increases hair's strength and gives better hair vitality.