The producers of Flash say that it "is an amplifying eyelash serum designed to give you long, beautiful lashes. The highly concentrated serum delivers benefits that you will begin to notice within a couple of weeks and with its once daily application, it’s simple too!"...
AND THEY AREN'T LYING!!!!!! I love this product and I have tried other growth serums that have not been great (ie stings and/or don't work). I followed the instructions and used it every other day for the first week (I guess this is to get your skin/eyes 'used' to it) then every day for 6 or so weeks till your lashes have grown and then 2-3 times a week. By following these instructions I have (months later) the most GORGEOUS long full lashes (and brows) ever!
I buy it online from Pharmacy Direct for the super cheap price of $48.90!!!! or at a Farmers sale (although they rarely have this product on sale BOO).
I first purchased fLash around 3 years ago on recommendation from my local pharmacy after having lash extensions that left me with very short eyelashes once the extensions had fallen out. It definitely takes around 4 weeks to be noticeable, but is worth the nightly discipline before bed. I have purchased since from Onceit at a slightly cheaper price, but in comparison to some of the other brands fLash is pretty reasonable.
Tips: If you use fLash regularly for the first four weeks you will notice a difference, just add it to your nightly beauty routine. If you want an even quicker fix - use morning and night but make sure you allow it to dry properly prior to putting on any powder foundation/eye makeup. Once you get to your desired length you can have a break for a few days to extend the life of the serum.