At GFZ developed pneumatic hammers generate repeatable energy-rich impulses for seismic applications. The impulse energy is concentrated below 1000 Hz. The coverage is around two hundred meters with a resolution of some meters. For operation only compressed air and a power supply of 24 V DC are necessary. The pneumatic hammers run on several tunnel boring machines. The robust seismic source is licensed to the Herrenknecht AG and is in use for prediction ahead in tunnel construction.