Milwaukee’s Super Saw-zall Reciprocating Saw, Model (6538-21) is fast and durable. The patented Gear Protecting Clutch extends gear and motor life by absorbing sudden blade lock-up. The 15-amp motor with Constant Power Technology maintains constant speed and power under cutting load. The saw has a Counter Balance Mechanism that produces extremely low vibration levels. This allows the contractor to work longer without becoming fatigued.