Signals that are too stong can affect the clarity of your TV signal as much as too weak a signal. When the analogue signal is switched off in the UK, the digital signal will be boosted from its current rate. This may mean that you had perfect signal before the switchover and then your digital picture breaks up or mosaics, this is where the Variable Aerial Attenuator comes in.
Its adjustable tuning means you need not worry about which attenuator to purchase, this will cover the full range that will be required.