This is an old military horse bit, I believe from Portugal.
It is made of steel which has an aged dark patina.
Its mouthpiece has a medium height port, its shape is similar to many Portugese and Brazilian ports
The cheeks are flat with shaped sides.
they have small half moon shaped snaffle rein slots by the mouthpiece and curb rein rings at their ends, so the bit would function as a pelham.
It has its original steel double link curb chain.
There are no maker's marks or stamps.
There is wear which forms a notch on the front edge of each cheek - I do not know how this came about

Dimensions : Mouthpiece 5" (13cm), Cheek length 7" (17.8cm)
Weight : 693g (1lb 8½oz)