You can always use the leftover hair later. If you are using hair over 18" you might need another pack.If you are getting fusion or micro then you will need to consult your stylist
Q8:How long does it last?
A : This hair can last for very long time depending on how you maintain it. Treat it like your own hair and take very good care of it in order to use longer.
If you buy 100% virgin hair and take good care of the hair, it can last for over one year.