Hello Manuela Thanks for your question. Yes, these virtual walls are suitable for your Roomba 974 :) Many greetings, Your iRobot Team

One lock is enough to cover an area, either around e.g. food bowl or shoes or as a line to lock a room or area, 2 devices therefore 2 x lock. There is no battery. Each unit requires 2 x AA batteries. These last a very long time, unit glows when batteries are empty.

Good day stragori With the virtual walls, areas can be closed off and openings up to 3 metres wide can be blocked. This way, the robot stays in the room that needs to be cleaned. The HALO mode can also be used to create protection zones of 1.2 metres around certain areas or objects. Heavily soiled areas cannot be defined with the Roomba 676, but you could press the Spot function (button on the Roomba) so that it cleans again within a radius of 1 metre. Many greetings, Your iRobot Team

I do not have any pets and cannot find any safety info regarding pets. The virtual wall provides barrier for up to 7 ft and i can imagine some type of RF signal is used and I would expect that safety standards of EU / US must have been applied to be compliant. I would recommend to find this and google :) Sorry, couldn't be of much help.

Thank you for reporting the error. The only difference is that the iRobot Roomba "Dual Mode" (Black) is a single Virtual Wall and the iRobot Roomba "Dual Mode" Twin Pack (Black) is a twin pack. Hence the price difference. The picture is correct and the number of items has been adjusted.