Yes it is adjustable. I actually got one for my chihuahua, after several weeks of not receiving it, they shipped me another. Two days later the other one showed up, so I have one extra. Actually two because I put it on him and took it right back off because my chihuahua is extremely overweight, and my kids had a fit and was scared it would kill the dog. You can adjust the setting higher or lower.
Sorry I just seen this, no it does not shock the dog. When the dog barks it emits a high pitched tone only the dog can hear. I guess they don't like the noise they hear when they bark so they don't bark. Atleast that's the way I understand it.
Can you tell me what brand-name this collar is? I would like to bid on it for my little Yorky but she is under 5 pounds and I know some of those type colors should not be used on dogs under a certain weight so I just wanted to look it up first