The inner surface of the plastic indicating head is made into a polygonal mirror surface, so the direction indicating device which can reflect light rays of various angles is very conspicuous.

Now they were peeking inside his brain to see if a mysterious shadow on a previous CT image might be an internal clot, or hematoma, at the rear of the skull, indicating a blow to the head.

If validation does work, you should receive an error indicating the "head" is not finished.