OLAPLEX’s patented technology has created the 4-IN-1 Moisture Mask, which made with professional-strength ceramides, oils, and 11 vital amino acids. This is an in salon treatment that will transform your hair! It smooths, eliminates frizz, repairs damage. I, personally, love using the the Olaplex No. 4 clarifying shampoo first, which removes any product build up and excess oil, then following it up with 10 minutes with the 4 in 1 treatment. I have also used just a smidge (like a pea size) of the this as a leave in conditioner, applied while my hair is wet. Mind. Blown.
On the flip side, Olaplex No.8 (Intense Repair Moisture Mask) will give you the same or very similar results except this a the DIY home version of the product. It comes in a 3.3 fl. oz. bottle and costs about $30. Again, I'd recommend using the No.4 clarifying shampoo, ALSO AROUND $30, first and then follow up with the moisture mask for 10+ min.
So basically 4 in 1 vs. No.8?? WIN. WIN.