What is a "Spec sheet" and can I use another solution?

A Spec sheet is: A garment specification (spec) sheet, or measurement table, is a technical document that contains all construction details of the garment. It looks like a technical diagram or a sketch of a garment, including all of its measurements. Spec sheets are used by designers to communicate design concepts to manufacturers.

*You can also upload the full Tech pack as long as spec sheets are part of it.

Alternatively you can manually input the various sizes of the garment you're looking to publish.