Arri is short for Arnold and Richter, German manufacturer of high quality 16mm and 35mm cameras. All Arri cameras have a registration pin, so even the bottom-end models provide a very steady image. Arri cameras include the 16S (non-sync); 16 BL (crystal-sync); 16 SR, 16 SR-II, and 16 SR-III (internal crystal-sync with microprocessor-controlled movement).