[16x16] [GlassDoors 1.9] [2.1].zip is a release file of the Minecraft resource pack GlassDoors ResourcePack Add-on, made for Minecraft 1.9-Snapshot. It was published on March 9, 2016 and is 0.5 MB in size. For the full description, screenshots and every other version, visit the GlassDoors ResourcePack Add-on resource pack page.
How to install: Put the .zip into .minecraft/resourcepacks (do not extract it) and enable it under Options → Resource Packs.