My hair: oily roots, dehydrated on the lengths, fine, frizzy and tangly. Not dyed, and I use heat and styling products rarely.
My stylist recommended this mask for me, when I asked her for a mask that is nourishing, but that won't weigh my hair down, especially since it is fine and gets oily easily.
Now, this mask is formulated for colour-treated hair, which my hair is not, but I find it works amazingly for me!
It is a lightweight mask, and you only need a dime-sized (50p) amount (the stylist's orders!) as it is a professional product. I have mid-length hair and use this from my ears down, working it in. Then leave it for about 4 mins.
It leaves my hair soft and smooth, definitely nourished, but not heavier. Every once in a while I use a thicker mask, maybe once a month/ 6 weeks.
You can use a conditioner after it, but it is not necessary - experiment to see what your hair needs best.
If you are looking for a light but moisturising mask, I recommend this one. It's about £14 if I remember correcty and has lasted me ages!