This is an excellent captcha tool if your objective is requiring a human being to enter and answer based on visual references. I chose this tool partly because it is touch friendly for mobile access needs. The only concern I experienced is having the Google Chrome extension of "Adblock Plus" blocked the display of the image in the Chrome browser only. the eFence tool works fantastic in all the other browsers, and once I temporarily disabled Adblock Plus the tool worked perfectly in Chrome too. I highly recommend this tool because it was easy to install. The documentation was clear, and the developers have taken a terrific approach to proving a person is submitting data. Configuring it in the Joomla Administrator console was a snap and it worked the first time I tried it.