An encryption error monitoring system for checking packets transmitted between a private network and an external network. The main cutting edge is a convexly curved line protruding toward the outside of a rake face viewed from the top and another convexly curved line extending toward the seat face, convexly curving from one end of the main cutting edge to the other, viewed from the side. When function data is thereafter received, the device executes a function indicated by the data. Other embodiments are described and claimed. A drain conduit defines a passageway in fluid communication with a lower portion of the interior space.