VizPak: Products is a very popular material library for Modo, which has now been ported to Blender and works natively with both Cycles and Eevee (though some features such as SSS and Anisotropy are Cycles only).
The materials are all physically-based and derived from measured values for maximum accuracy and realism, this means that the metals for example have the correct colours and reflectance values and that zinc is distinct from steel.
The materials are the result of many years of research and careful analysis, and are more realistic than most other libraries. Every material has been carefully built from scratch in Blender.
The library is being launched with a 25% discount until the 5th of February, use the code vizpak at checkout
Find out more at the following links: