Used this for an EMT course, and they worked well -- maybe not as well as some of the higher end models but great for sampling breathing sounds and heart beats. The build quality is great as they're powerful (tapping on it will blow your ears out so don't). Miss those pre-med days already reviewing this product! Cheap and efficient on Amazon you won't find it cheaper elsewhere, and trust me you won't want used ones on ebay as I've had friends buy them with ear gunk left on them.