The Clamp-On Ammeter has a great Jaw opening that can easily fit the power mains on your home electric meter. This only Measures AC amperes, though. The other meter functions are easy to use, and the accuracy is surprisingly good, for this price level. The included Separate Non-Contact Volt (NCV) Detecor just doesn't work at all. But the Jaws on the Clamp-On Meter have an NCV sensor, and the NCV function works pretty well. I already have a different NCV detector thet works great, so no worries. This Clamp-On Meter is actually surprisingly good, It was a good purchase.