Hohner Echo

Hi Kinya !!!!

A friend picked up an old Hohner Echo for me at an antique sale. 

Although it's a bit rough with obvious dirt and rust on the cover plates which are slightly up on both ends I find it very intriguing and will apply some of my learned harp tech skills to it. 

My question is , what do I have?

key of G Echo Hohner, with a half moon type shape at the whole side.

there are four embossed enscriptions. 

Grand Prix Geneva 1927

Grand Prix Philad. 1926

Grand Prix Paris 1937

Grand Prix Chicago (date worn off)

in the centre is an enscription that says Trade- Mark over two hands holding a 'coin' which has Gesetze over Gesch

Any ideas ???