Feature Level 11.1 is a specification that defines a set of features and capabilities that a graphics processing unit (GPU) must support to be considered compatible with DirectX 11.1. This feature level includes various enhancements over its predecessors, such as:
Since there is no single installer, you can ensure it is active by following these steps: Windows Update : Most users get the latest DirectX runtimes through Windows Update . Ensure your OS is fully updated. DirectX End-User Runtime d3d feature level 11.1 download
The good news is that you don't need to download D3D Feature Level 11.1 separately. It is included in the following: Feature Level 11