Sigma and Cateye are both great computers; I've had both, l liked both. I chose the Sigma the second time around because it had a backlight, battery power display, battery back up in case battery dies or changing bats you won't lose all your information or settings, current temperature, and will compare current speed with average speed. The Sigma just had more features. It's very water resistant, my wife has one on her bike and it sits outside getting rained on a lot, but so is the Cateye. The Cateye is about $9 less expensive. So if you want all the features I mentioned that the Sigma has then spend the additonal $9, if you have no need for that stuff then get the Cateye.