This unit has clear step-by-step instructions but lacks a diagram. There are eight LEDs on a scale clearly labelled ‘Weak’, ‘OK’ and ‘Strong’, making the signal easy to read. It took a few seconds to find the strongest signal – a top strength of four lights gave us a perfect picture. A 9V battery and adaptor lead are supplied. The only niggle is the price, but it would still make a good buy.