Klein Tools NCVT1PKIT Electrical Tester Kit with Non-Contact Low Voltage Tester, 50 to 1000V AC and GFCI Receptacle Tester, 2-Piece

Great bit of kit if you want to stay alive when testing your outlets and cables

Worked great for 2 months then started blinking red and green even with new batteries. Klein tools surprisingly not helpful. DO NOT BUY. Follow up- outside Amazon return window but contacted Klein tools who replaced with new tool. Rating increased.

These are simple and easy to use. Touch the probe to a wire and see if its live. In the past, if a wire was coated with drywall mud as sometimes happen in a newer house, it was hard to use my old tester to see if it was live. With this, touch the porbe to wire and you know instantly. I have used the plug in electrical tester to check polarity and check an outlet. I have a combo leaf blower vacuum and if the vacuum attachment is not put on just exactly, it won't turn on, even though it looks like it fits correctly. Not sure if its the vacuum or the gfi outlet. With the tester it's a snap.

I only use the tester being in the plumbing field to test to see if there's power going to whatever I'm working on and it hasn't let me down yet

This thing is a life saver. It works great. The GFCi tester works well for child safety outlets