Knaack. Compatible with any brand or style of jobsite box, the PowerCrew 15-amp in-box power supply is a safer in-box power solution that nearly eliminates the risk of shock and fire, the maker says. Four GCFI-protected outlets provide 15 amps for operating tools or charging batteries. The power source comes via a standard three-prong extension cord that plugs into the outside of the box, replacing unsafe practices such as drilling holes through boxes for power cords. The UL-listed PowerCrew’s safety features include an internal relay that senses broken wires in the power supply and LEDs that indicate the outlets have power. 800.456.7865.