This is a hand forged heavy steel with a dark aged patina.
It is very heavy and was probably made for a farm or draft horse.
It is a straight bar loose ring snaffle with a central rotating disc.
The disc has a pendant with three holes in it
Metal "keys" or players could be attached through these holes.
Such bits were used when breaking in, the moving parts were supposed to encourage the young horse to relax its mouth. I have seen similar bits described as "tickler" bits

Dimensions of bit : Mouthpiece 14cm (5½")
Weight 879g (1 lb 15 oz)