One of the major issues in using any form of electrotherapy, exception being Infrex Plus due to short duration of treatment, is protecting ones skin when a self adhering electrode is covering the skin for hours at a time is skin protection.  This is especially true with a tens unit      The nice aspect of owning an Infrex Plus which also has a tens mode is the insurance companies will buy the skin protection, as well as topical pain products for the patient as long as the patient has chronic pain.