Sometimes, you need to see behind walls and in dark, confined areas. The Tek4 Inspection Scope, powered by a 4-volt lithium-ion battery, offers a digital zoom with up to 2X magnification, a 3-foot-long cable, and a high-resolution 2.7-inch LCD screen. It offers five hours of continuous runtime and can be submerged in water for up to 30 minutes.  Cost: $139. Ryobi Power Tools. 800-525-2579.