When sourcing a 1-inch impact wrench, the most critical factor is the Max Torque, which for industrial grades should range between 2,500 Nm to 4,500 Nm. You must also verify the Air Consumption (CFM) to ensure it matches your compressor's output. Look for a Twin Hammer mechanism for high-torque stability or a Pinless Clutch for maximum durability in heavy-truck maintenance. Additionally, ensure the Anvil length (standard vs. extended) suits your specific usage scenario, such as deep-dish wheel nut removal.