Inspect Cross Holes - Check Internal Bores - Look in Mold Cavities

A Borescope is an optical device consisting of a rigid or flexible
tube with an eyepiece on one end, an objective lens on the other
linked together by a relay optical system in between. The optical system is usually surrounded by optical fibers used for illumination 
of the remote object.  An internal image of the illuminated object is formed by the objective lens and magnified by the eyepiece which
presents it to the viewer's eye. Rigid or flexible borescopes may be fitted with a video or CCD camera.