What can help you straight your hair ?

Naturally my hair is really wavy/curly and it can be a pain in the a** when I'm traying to make it straight. There are a lot of products to help you make your hair straight, but i didn't have big/any results whit most of them. I saw a product by Balea - a DM brand /German/, that can be found in any DM store in Europe. It looks like this and it cost around 4.00 euro /and here the others cost twice that much, at least/

How do I use it ? After I've washed my hair, I just put some in my hand /my hair is long-it passes my waist when straight/ - as big as a chessnut and put it all around in my hair and then 1) I blow-dry my hair - meaning i dry my hear and straighten it at the same time 2) i go to sleep and straighten it whit the straighter in the morning And this thing really helps my hair stay straight for a longer time, than if I don't use it. If i don't use it - the effect is visibale for the next 15 minutes at maximum and if I use it /depending on the wather/ it hold up until I wash my hair again, witch is great ^ ^