Prolongs Smoothing Treatment. Apply pulp infused. Sodium chloride free Xtend Color Lock Keratin Replenishing Mask is a deep penetrating repair mask. This luxurious product will repair and revive damaged, brittle, stressed hair. You may use Xtend Color Lock Keratin Replenishing Mask to repair damaged, lifeless, or stressed hair. This product can be used on hair treated with or without a keratin treatment and is safe for all hair types. Not Tested on Animals. .