How to implement correctly to implement the characteristics of the product?

Question

WooCommerce

Hello!
How to correctly implement the characteristics of color and length (see screen)?
These characteristics will be the same for all variations.

Through attributes and pre-prepared values, I implemented Diameter and Material, and based on these attributes, variable products are formed.
I tried to add a characteristic through attributes, but you can’t just enter a value there, you need to add it in advance.
Maybe I'm doing something wrong?)

Is it really only through additional fields?

layout