If you mean the Heart Rate Monitor, yes I have one. I use it for my cardio. I run alot and I like to train in a certain heart rate zone. It is fairly low intensity for me but every one is different. You will read alot about high intensity and low intensity, just pick which one works best for you. It helped me considerably increase both speed and disctance. I run every other day and do Max ot in between. My long funs once a week are over 10 miles and my regular ones are 5 miles.
It helped me lose a lot of weight, 130 lbs in a little over a year. I swear by mine. I have the cheapo Timex version. I like it because you can easily change the battery in the chest strap which needs it every 6 months or so.