not at all accurate

I tried using this product twice, but had to return it because it was way off. It underestimated the distance I ran by about 10%.

I found this out because according to the Forerunner, I ran my slowest 5K ever. But when I used mapmyrun.com, I found that I actually ran 3.4 miles, instead of the 3.1 that the Forerunner calculated. The whole point of the Forerunner is to measure your distance, and if it doesn't do that correctly, it is pointless.

Giving it the benefit of the doubt, I did run through some moderate tree cover. So, maybe that was the problem (although, all the documentation says it has great reception, even through tree cover and tall buildings).