Yes, It emits a very small shock at first and gradually increases if the dog continues to bark. I believe it resets its self after so much time. It is also for a large breed dog I did forget to mention that.
That sounds a tad bit cruel, doesn't it? I mean, what if the dog is barking because he's in pain, or if he's hungry or thirsty? Dogs usually bark when they need something.
it's not meant to hurt them. be sure the volume is turned very low, like half of 1. dogs are easily trainable. then soon, keep the collar on, but take the batteries out of the control switch & clap instead. sometimes you don't have to do anything. they remember.