1) Electric dot marking machine:

Does not require any compressed air, but the pin vibrates in a much lower frequency so it marks much slower and shallower.

FIXAL is not selling this kind of  Electric dot marking machine .

2) Pneumatic dot marking machine: 

Requires compressed air, the pin vibrates in a much higher frequency so it marks much faster and deeper.

FIXAL is selling this kind of Pneumatic dot marking machine.