What is m-tank?

As an AI language model, I don't have specific information about the term "m-tank". It could refer to various things such as:

• A type of mobile tank used in the military
• A type of fuel tank used in vehicles that run on methane gas
• A brand name for a water storage tank or septic tank

Without more context, it's hard to provide a specific explanation of what "m-tank" refers to.