The mower operates with LR06 battery (AA) that is provided. Operation is simple and intuitive, no hairs plucked as is too often the case on other devices, but after all relative effectiveness (it must pass many times, which is not very serious in remaining.)
In addition, currently (March 2015), the price is quite high, and even harder to explain in relation to other similar products, including Philips. See this design, it also, or the simple version and no frills, just 3 times cheaper ...
It is hoped that it will drop pretty quickly.