The high-performance rotary handle mechanism uses a simple, yet robust design to make installation and operation easy. The external handles key functional components are all metallic, ensuring reliability. The metalon-metal interface between the handle and shaft prevents contaminant buildup that could impede operation, while UV and chemical agent resistant materials protect the handle from heat and fading in direct sunlight, as well as chemicals that may be introduced in harsh environments. The handle mechanism has stand-off support that allows for easy operation with a gloved hand. With a shallow profile, the handle can easily be used in applications where an internal or double door is required. The high-performance external handle can accept padlocks or multi-hasp locks. The door is interlocked when padlocked and cannot be bypassed.