This is the first StunMaster I've owned, so I can't compare it to previous models. What caught my interest in this particular model was a "multi function" stungun. It comes with the stunner, a LED light, emergency flashers, a alarm/siren and pull-cord that deactivates the stunner if someone was to take it from you by force.
The stunner is loud when activated by a small red button on the side. The spark is the length of the small LED light mounted in between the two large shock prods. Even though the spark sounds quite loud, I feel as if a previous stun gun I owned (black cobra 800,000 Volts) was louder, and had a longer spark arch. If it's true that this stunner has 2.7Mil-V of power, my guess is that the stunmaster is still a better choice.
The LED light is a nice addition. Now you might actually use this thing you're always carrying with you. It could however be brighter, as the 1 LED light just doesn't pack much of a punch.
The siren is pathetic. It isn't very loud at all, and doubt you'll be able to scare someone away with it. This would've been a great addition if it was about 10 times louder.
I'm not sure what good the flashers do, and they're not very bright either. If they had implemented strobes instead of some faint led light, this also would've been a great addition.
The construction seems solid, and the size even though not as compact as some stunguns, is still small enough to carry comfortably. The top red round button you can see is the stun button. It's flush with the grip, so might be hard to find if you've got adrenaline pumping through you if you're in danger. The previous stungun I had had a trigger, so it was easy to feel it without looking at the device first.
The internal rechargeable batteries are great, but if they were to get worn out your stungun would be worthless. At least, from what I've read, Stunmaster gives you a lifetime warranty, so hopefully they could replace those batteries if that was to happen.
I haven't used it on anyone so far and hope I never have to, but all and all it looks like a decent stungun.