How to sell some items by size?

[win7hkr]

Hello,
Would anyone know how to set the product up to sell by size?
Like with a check box for something like
Scented oil 1oz
Scented oil 2oz
Scented oil 3oz and ect ect. We need at least 5 feilds and or check box on each product and on some products we do not need size in oz we just sell one item. But for others we sell it by the oz or lb and have several sizes.

Like what this site does

http://www.naturesgardencandles.com/...rance-Oil.html

Thank you for helping me I am going nuts on this!

[niccol]

You want to use attributes:

https://www.zen-cart.com/tutorials/index.php?article=57