Sorry but this is a poor product. Yes cheap price but = cheap product.
Based on an assumption that every Pin is exactly the same height (6m) and uses a changeable vertical 'height' bar (operated by clicking the button seen on top of the model) to match the height of the Pin and, by using basic mathematics (Pythagoras Principal) estimates the distance. Problem is that if the Pins are different heights, then the mathematics fail and the readings are pointless. You can be anywhere between 10 and 20% out in true distance.”