This is an old nickel military Portsmouth or Elbow horse bit
This design was used by the military because it was a "universal" bit - the reversible mouthpiece and choice of rein slots made it suitable for many different horses.
It has a half-twisted or reversible mouthpiece with a low port.
The mouthpiece is faintly stamped "Sold Nickel".
Each cheek has two slots for the curb rein.
The bit still has its original curb hooks but one is bent out of shape.
This bit shows extensive wear around the joints between the mouthpiece and the cheeks. The curb rein slots are also worn..
Dimensions : Mouthpiece 4¼" (10.7cm),
Cheek length 6" (15cm)
Weight : 433g (15¼oz)
Ref : bit740