Hi Ashok,
I have been using Nanogen for the past 2 yrs. I get it from Richfeel for about 1900 for 12g. The basic requirement for a concealer to work is that the scalp should have some hair to hold it. I have been using it for 2 yrs and no one has ever detected it. I have been extremely happy with it however i really want to stop it as I have to shampoo my hair everyday.
Regards,
Sandip