Rejuvenol Brazilian Keratin Treatment Boosted straightening treatment softens and smooths coarse resistant hair with double the power. The Brazilian Keratin Treatment Boosted is designed for coarse, resistant, and extreme curly hair and provides 50% more straightening power than the original Rejuvenol Brazilian Keratin Treatment. Rejuvenol Brazilian Keratin Treatment with Collagen is a revolutionary treatment for all kinds of hair. It contains collagen to help maintain the strength and flexibility of the hair. Your hair will be shiny, healthy and manageable.