Single joined olive bit coated with sweet iron.
Sweet iron is an alloy of black iron and copper, which is characterised by a sweetish taste, slightly stimulating to salivation. The alloy is non-toxic and harmless to horses.
The sweet iron will oxidize and tarnish, and with time the bit will lose its blue color.
The remaining parts of the bit (including rings) are made of stainless steel, resistant to rust.