Maximum (or Minimum) Product Quantity

It is critical I limit the quantity of each product I sell per transaction - ie they can only buy a maximum quantity of 8 Item Z’s per order. I see a few feature requests for this, but haven’t found any code - has anyone figured this out?!

I’m thinking something on the product page that would say: If product quantity is greater than (value), display “maximum quantity allowed” message and disable the add to cart button?
I can’t seem to find the object name for that field.
HELP!