They are Feather AC type blades which look like very long injector blades and even come in a very long injector blade cartridge. Italian Barber should carry them and so does Amazon or almost any other shaving mail order.
All I've used in mine is the Feather Pro (black box in above post) for 10 or so easy BBS shaves. The Hawk has become constantly one of the four razors loaded up on the sink seeing use about every other day.