Buy the Olaplex N°.9 Bond Protector™ Hair Serum.

It repairs hair instead of just coating it, and that is worth more than a cheaper price tag per ounce.

What was compared

1. Fixes damage, does not just hide it
Olaplex uses a patented bond-building ingredient that rebuilds broken disulfide bonds in bleached or color-treated hair, while Paul Mitchell's serum is a silicone-based smoother that only sits on top. If you color or bleach your hair, that is actual repair versus a temporary mask.
2. Skip the clarifying wash Paul Mitchell forces
Paul Mitchell's silicone-heavy formula needs a clarifying shampoo every 2-3 weeks to stop buildup, per its own users. Olaplex's silicone-free formula does not build up, so you are not buying a second product just to undo the first.
3. You know exactly how hot is safe
Olaplex states a hard number: protection up to 450F/232C, covering basically every flat iron and blow dryer setting. Paul Mitchell's listing gives no such figure, so you are guessing whether your tool is within range.
4. Olaplex stays good, Paul Mitchell went backward
Recent reviews of Paul Mitchell's reformulated serum call it meh and say it lost the shine and softness it used to give. Olaplex keeps earning consistent praise for shine and smoothness, plus an Allure Best of Beauty seal.
5. Cheaper per ounce, costlier in the end
Paul Mitchell runs $4.65 per fl oz against Olaplex's $10.67, a real gap on paper. But Olaplex is a concentrated drop-in serum, one bottle lasts over a year for most users, and you are not also buying clarifying shampoo to manage silicone buildup like you are with Paul Mitchell.