I am currently using an EBI bone growth stimulator for a tibia nonunion.  The current EBI simulators are good for 400 days from date of first use.  After that they go "brain dead" and will not operate.  They must be reset by the company.  They are also sold by EBI as prescription only and should never be used without a doctors supervision.  It is my understanding that the pulse width and frequency of the pulses are specific to the bone being treated to and the reason for treatment. If not used properly they can cause more harm then good...or so my doctor tell me.  If you feel you need one of these without medical supervision, at least find out the date of first use and what bone and specific condition (nonunion, bone graft, oestoprosis, etc) and what specific bone the unit was originally prescribed for.