Are there Depends made for men who are over 300 pounds?

We now have a problem when we take Dad to the Dr or anywhere else that takes us away from home for a while. So it's time to do something different when we go out.

However, I'm not sure where to even start looking for Depends in a 3x size. I've only seen small/medium or large at the drugstore or Wal-Mart.

Also, one of our caregivers suggested that we buy Dad some pants with snaps up and down the side of the legs. Does anyone know of a place to order pants like these?

Thanks for any suggestions!