Armature Suitable 6-100 Grinders and Similar Models and 100% H Class DC Copper A Grade Used. Copper Temperature Capacity 200 degree Celcious and More. Gel on Commutator Root to avoid dust and Concrete hit to Protect Damaging Wire. Shaft Made by CNC accurate Size in Micron to fit Bearing Properly to avoid Vibration. Commutator Specially deisgned for Dollor cut power tools for High Durable Life.