This product was one of my first experiences with Kiehl's. As it says, it's a micro-exfoliating scalp treatment, which is meant to alleviate build-up with apricot seed and argan shells and promote scalp health with additional vitamins and minerals.
For reference- I have long, relatively thick hair and I tend to get a lot of buildup at the scalp. When I first applied this product I was very disappointed. The exfoliating bits are much more sparse than I was expecting them to be. In the picture below, you can see the pieces of apricot seeds; the argan shells are white and are present in about equal amounts. I find that the the argan shell pieces are slightly more delicate.
Along with being surprised about the sparsity of the exfoliants, I felt like my long, thick hair made it difficult to apply. I was doing the best I could to massage it into my scalp, but I wasn't feeling like I was getting close enough for it to provide exfoliation. I guess I was expecting it to feel like I was using St. Ives on my scalp. This product contains ingredients like menthol and rosemary oil, which gives a nice cooling/tingling effect. It also contains vitreoscilla ferment, which has been shown to increase oxygen utilization in cells; however, studies have only been carried out in vitro (i.e. in a test tube), so it's not yet been proven to be beneficial to the skin. The product is meant to sit of up to 5 minutes (I go for 3-5) right before shampooing.
Though I wasn't expecting much, I did see results from this product. It definitely helped to clarify and balance my scalp. My roots felt softer and not as weighed down, so I was able to get more volume at the roots. I was definitely happy to see that this product wasn't a giant fail, because aside from the tingle, I couldn't feel it working. This is described as a potent treatment, but I found it to be very gentle...almost too gentle, but I guess you can't argue with results. Thinking more about it, a harsher exfoliant may be too damaging to the hair, especially for people with longer hair who have difficulties getting the product to the scalp (me!). If you are looking for a harsher scrub for volume, I would recommend Lush's Big Shampoo; however, it's not going to do great things for the health of your hair (though it's great for occasional use).
Overall, I would recommend this or a similar product to people who struggle with scalp buildup or dandruff. I would say not to be discouraged if you aren't feeling the exfoliants, just massage the product in as best you can, and you should see results. Again, it is clarifying and balancing and will give you some volume without damaging your hair. I think this is a pretty unique product; however, Ouidad has a scalp exfoliant with a similar price ($6 an oz compared to Kiehl's $5.88 an oz, but Ouidad's is double the size) that I might try before I repurchase this one; it's a little bit more accessible.
You can find this product at kiehls.com where it retails for $20.