This is the most watched "how to" tens video on "how to use a tens unit", transcutaneous electronic nerve stimulator, on YouTube.  This tns video teaches chronic pain patients, how to actually use a tens unit including instructions on what the various control features are and why they are used.  In this specific it's the Digital 6000 Tens unit from MedFaxx however the tens video easily shows anyone how to use practically any generic tens unit. On internet search results this is the most viewed educatonal tens video.

   The corresponding video to how to use Tens mode or Interferential mode on the Infrex Plus can be seen on this video, Using Tens Mode On The Infrex Plus unit.