Its always advisable to review all products before purchasing and installing. Biggest mistake alot of people make is to purchase based on TV Lines, however TV Lines is irrelevant if the chipset is not of any quality. We have installed systems in the past with 500TVL with quality chipset and lens that show better images day and night than 600-700TVL out of the box kits. It pays to know what you are installing and if in doubt there is many companies who will be more than happy to provide you with all the information you need, including us.