Drop Down Menus for Products

I am looking for a method of adding a selection of one of multiple attributes for an individual product or product type when they are purchased. A specific example would be the purchase of a ring where the size could be specified, or the length of a necklace.

I assume that this functionality is probably available through a mod, and a point in the right direction would be extremely helpful. Thanks!

the purchase of a ring where the size could be specified, or the length of a necklace.

I assume that this functionality is probably available through a mo
No mod for this as it is builtin

The tutorial link above right is a resource for these basic often asked questions

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