_64x__Black_Pack.zip is a release file of the Minecraft resource pack Black Pack [64x], made for Minecraft 1.7.4. It was published on March 5, 2014 and is 5.5 MB in size. For the full description, screenshots and every other version, visit the Black Pack [64x] resource pack page.
How to install: Put the .zip into .minecraft/resourcepacks (do not extract it) and enable it under Options → Resource Packs.