Hardened bones from the fingertips are shot at the enemy, with a spinning motion added to the skeletal bullets. A direct hit will excavate skin, flesh, and bone. Since the bones of the user can be regenerated, the rate of fire from the user's arsenal is limitless. This technique is essential to Kimimaro for his long distance attacks.
The first two kanji would normally be pronounced as jisshi (じっし) or jusshi (じゅっし), rather than the teshi (てし) given by the furigana. Teshi probably comes from shushi (手指, finger), the first kanji of which can also be pronounced as te.