Some might like the IF stim types even better.. (IF = interferential)

[Interferential Stimulators
Primarily used to manage deep chronic pain, Interferential current uses very high pulse rate, usually 4001 - 4150 pulses per second. This higher frequency goes through the skin and muscle better than TENS or other modalities, thus can be more effective in pain control. Provides more analgesic, or nerve blocking effect.
]
http://www.medi-stim.com/stims/if.html
http://www.ib3health.com/products/Te...TypesEMS.shtml


Here is combo machines - Combination TENS Unit, Muscle Stimulator, Interferential Unit, and Micro Current Device - plug in or battery use.
http://www.otcwholesale.com/koalaty-...ml#proddetails
http://www.amazon.com/Lifetime-warra...QZXNKX4YPGZEMV