I bought this after a recommendation from a YouTuber. It’s very easy to use, just take one of those small bottles - pour into the bottle - fill up to the line with water.
I spray it on my hair and let it sit for at least 10 minutes before I wash my hair. The first few times I used the product, I didn’t introduce any other products to see what the difference is.
As the title says: My hair feels significantly thicker and has a healthy "weight" - which is positive since it can easily become flyaway and doesn’t look as uniform and nice. My impression is also that it helps my hair retain moisture - provided that I first do my usual with conditioner/leave-in conditioner/hair oil.
When it comes to how many times one can use it before it runs out, it depends a lot on how thick your hair is. The spray in the bottle creates a nice mist that spreads well, but according to the instructions, one should ensure that the entire hair is thoroughly moistened.
To be a bit economical, I do it so that it’s really moist, and not so it looks as wet as some do online.
I bought this kit about two months ago and still have some left in the bottle (but there’s probably only one use left). I haven’t used it with every hair wash, but about once a week (wash about two, three times).
If one has extra money for such a product, I definitely think it’s a fantastic product. Just bought two refill kits (=four bottles).