The Hatsan Harpoon is designed to be compatible with commercially-available crossbow arrows to eliminate the need to purchase expensive, specialized arrows. The airgun is designed to fire 20? long arrows with an inner diameter of 0.300-0.305? (7.62-7.75mm). This matches the size of popular 2219 type arrows that can be found at many sporting goods stores.
Due to the Harpoon’s high power output, Hatsan recommends using aluminum arrows.
Product manual available HERE.