This wrench has internal parts of poor quality. The mechanicsm is driven off a small rubber belt. Mine worked approximately 3 weeks. Then, when the button to move the jaw was used, the motor would run but no jaw movement. I removed the screws from the plastic casing to find the belt had broke in two pieces. It appeared to be dry-rotted. It is a cheep internal part that, when breaks, renders the entire tool no more valuable than the $5 crescent wrench from Walmart. Don't waste your money.