Most sites listed here include an e-mail link to contact the developer. Before making your selection you will want to spend a fair amount of time reviewing product information found on site, or by request. The software companies have targeted schools and business users. NetNanny and Cyber Patrol have home use versions. Most of the software developers have on-line help desk and provide a toll free number.
Filters are only as accurate as their last update.
There will always be those who can beat the filter. Look for filter quality to improve in both browser and stand alone software, as demand increases. An alternative to the filter is the software called WebWacker. You create a customized database of web sites that you select. Interface your web browser to the database, and the web user can only access the sites that are stored in the database.