You need to buy screws with diferent dimensions to fix something you have at home
in this module you have a page with this title "Screw"
In this page you have a image of a normal metal screw but below that image you have alot of dimensions and diametre for this same screw
The more you buy the less you pay for every screw (EX: for every 50 screws you buy you pay 1 less cent for unit)
I hope you guys understand what i want
HELP!
Not a module.... Use normal VM custom fields for sizes in conjunction with a quantity discount plugin.
Search/read the forum & the docs. eg http://docs.virtuemart.net/manual/general-concepts/212-customfields.html
If you have not many product to set, you can use multiple prices.