Declared Weight EKL

Hello community,

I have a product with a KESP (Knowledge Engineering Specification Physical).

The product consists of multiple 3D-parts.

I'm trying to write a rule which fetches the Declared weight (MASS-value) of my product and add it to my string-parameter. The declared weight can be found in the B.I Essentials>Weight Definition. 

The declared value is already linked to the computed weight of the product.

Have anyone any ideas? Would be grateful for help.

Best regards,

William