Boresight Telescope Mark VIII Mod 6
Designed for naval ordnance, this Boresight Telescope, made by Spencer Lens Co., was used to align the bore of a naval gun to its distally-mounted gunsight along the specified firing range. The telescope was positioned within the bore of the gun during the sighting procedure, to align the line of firing with the line of the gunsight, intersecting them along the specified firing range. Used for sighting 3"/50 guns.
The case measures 12.5 inches long, by ~4.5 inches wide and deep.