Product Specifications Tab

Hi,

I hear mention of this in the forums, but I don't see it as an option on the products admin area.  Is there a way to add it or turn it on?  

Using Version 4.2

I would like to be able to add specs, like dementions, weight, etc for the products.

Thanks in advance!

If the shipping is enabled for the product then you can add properties like weight, length, width, and height in the shipping section of the product detail page which are required for the shipping rate calculation(3rd section/tab in the product detail page).
If you want some other custom attributes you can use the product attributes section in the product detail page(6th section/tab in the product detail page). To map the product with the product attributes, you need to create the attributes first.  Read more about the product attributes here

You can check the demo store for the dimension and product attributes feature here