What can high-end Division Tech be used for?
Standard (green) Division Tech can be used for crafting Specialized (blue) ingredients.
Specialized (blue) Division Tech can be used for crafting High-end (gold) ingredients.
But what can High-end (gold) Division Tech be used for?
The high-end Division Tech is a requirement for crafting items which come from a recipe bought from a Dark Zone vendor.
Here is a screen capture of a Dark Zone recipe. Where you can see on the right that it requires high-end Division Tech as a crafting material.
Youtube.com - Guide To Maxing Out Character, Level 31 Items