Master's armor repair kit is a tool in The Witcher 3: Wild Hunt that repairs 90% durability on armors.
Simply drag the icon onto the armor piece in need of repair in the inventory screen, or right-click on the kit and choose the item to be repaired.
Crafting Requirements 
It can be purchased from the following merchants:
- All armorers in Novigrad, Oxenfurt, Skellige and Toussaint
- Merchant at the sawmill northeast of Rannvaig
- Merchant in Mohrin Village
