Please note not all hair type

I bought most expensive in supermarkets.
I have fine hair, wavy and squared.
My type of hair would suit this type of device, according to their questionnaire online.
But it is quite difficult to handle: the handling and especially the technique is time consuming and not practical because the root treated is mixed with the rest of the hair is left on the other side.
In the result, my hair is brightened slightly but nothing whopping like the woman you see in the pub.
Besides my beautiful ripples have become stiff and dry.
I think it would be well suited to a semi-long hair and stiff at the base.
I'll return it because it does not suit me at all.