So you have a factory or warehouse, and you currently have 400W Metal Halide or HPS fixtures, and you are thinking to convert over to LED. But you want to make sure that the light levels are good before you buy? How can you be sure?
Source: https://www.myledlightingguide.com/blog-photometric-results-to-replace-400w-metal-halide-fixture
source https://myledlightingguide1.wordpress.com/2018/04/30/photometric-results-to-replace-400w-metal-halide-warehouse-light/