Voucher limited to quantity of product

[Luca S.]

Hi guys,
how to limit a voucher to quantity of a products?

I want sell for free a product for promotion, but only for 1 quantity ehehhe. But looks my problem..

I created an hided category and added 1 product, so customers that buy the product inside that category with a voucher they can obtain 100% of discount on price product, but i want limit to 1 quantity! Because from cart, people can add more quantity and obtain 100% of discount on X quantity… ehehhee

Thanks