The heartrate display isn't always accurate. I paid the extra $30 so I could have the heartrate displayed. I should have stuck with the standard radar without the lcd screen for less than $30.
it has one song on it. the instructions are minimal and pretty bad, seems to have been translated from a different language without being corrected for errors or clarity. I am not sure what the "build in battery" is but you have to power it with 4 AAA. Get more detail about AngelSound Basic Fetal Heart Doppler, Build In Battery, LCD Screen.
