Does not work
This product is terrible. The current is really weak, so there is a relatively long delay before the flies die. During this time, they can just fly away to safety.

A regular fly swatter is much more effective.

Flys? notsomuch, but super on roaches
Depress the button and get excited when you see how well these things do with roaches. Instead of a splat and crunch, all you'll get is a small pop, a little spark, and a stunned roach that sticks to the coil when can then be easily carried to a toilet and flushed without even wasting a paper towel. Buy a bunch and give to all your friends. They may be skeptical at first but it is easily the best invention since sliced bread :)

This thing is suppose to kill flys?
This thing is worthless, I actually trapped a fly against a window and it crawled through the wire mesh and got out! The button was pushed and nothing happened. I even went as far and got my multimeter out and checked the voltage (measured around 8 volts) on the wires. Not sure how this thing is suppose to kill bugs at 8 volts. I was doubtful prior to purchase but read the postive reviews and decided to try it out. One of those live and learn type of experiences.

Cheaply Made
Arrived at my door in broken pieces. The handle, which holds the batteries, is made of very thin cheap plastic. Spend a few more dollars and get a zapper such as the Charcoal Companion Amazing Bug Zapper which is sturdier and works very well.

Doesn't work!
I was not expecting too much, but even so, I was extremely disappointed with this product. It simply does NOT work. The electrical current is weak. I couldn't kill one single fly. Once, one of the flies I was trying to kill became dizzy and started to walk on the floor, but a few seconds later it took off again. Buying this product is a waste of money and time!