Yup, polar is what I have.
yes, like kollision said, some treadmills and whatnot have them built in, but from my experience the ones in my gym are usually either inaccurate or always broken.
Plus, sometimes I do my cardio jogging in my neighbourhood, in which case I would need my own monitor anyway.
I have the one with the chest strap and watch. I think if you are a female looking to reduce boy fat while retaining lean muscle, it is a good investment.
The formula by the way for figuring out where your fat burning range is simply
220 - (your age) = your max heart rate. he multiply that number by 65% and by 75%. Keep your rate between those two numbers while doing cardio, and you will burn fat not muscle.
So for me it would be 220 - 30 (i.e. my age) = 190.
190 X 65% = 123.5
190 X 75% = 142.5
I keep my heart rate between these two numbers (which is my "fat burning range" and I burn fat not hard earned muscle). And I use my heart rate monitor to keep track of my heart rate, making sure it is where it should be.
You will find that as you get more cardiovascularly fit, it will take greater intensity to bring your heart rate up to the right numbers, and that is good because it means your heart is getting fitter!!
At least that is what I do -- it works for me!!