This tool allows you to determine the maximum number of IP's you would like to have blocked at any given time. When the list fills up old IP's are removed and new IP's are inserted. This is how you can control the rate of IP's leaving and entering your exclusion lists.
The range is customizable. The minimum our system can refresh at is 50 IP addresses and the maximum is 500 IP addresses (in accordance with Google's maximum IP list length).
Put simply- if there is a client that has 1000 total clicks monthly but only 10 fraudulent clicks (10 blocked IP's) and he stays with the standard 500 IP list rate that Google offers, those 10 IP addresses will virtually be blocked forever (since it would take 50 months to replace them). He can lower the refresh rate and make those IP's leave his exclusion list at a much faster rate.