While it is claimed not to cause burns under "ordinary use", it is also described as being similar to that of an incandescent light bulb being pressed against the skin, which can cause severe burns in just a few seconds. The beam can be focused up to 700 meters away, and is said to penetrate thick clothing although not walls. At 95 GHz, the frequency is much higher than the 2.45 GHz of a microwave oven. This frequency was chosen because it penetrates less than 1/64 of an inch (0.4 mm), which – in most humans, except for eyelids and babies – avoids the second skin layer (the dermis) where critical structures are found such as nerve endings and blood vessels.