This is a small mechanical Klaxon Horn. Size 6″ x 5″.
Used in the mining industry to alert men to the dangers of moving machinery such as coal cutters etc or maybe to be alerted to any shotfiring. They were housed in a steel box with a lever to press to activate the plunger on the Klaxon, the box was to keep them free of dust, I don`t believe they were in use for long? I had one similar to this given to me by my Brother taken from Cwmtillery Colliery in the late 1960s.