Google "improve leg circulation" and you may see sponsored ads for electronic muscle stimulators that claim to boost blood flow to your feet. But is there any evidence they work? Peripheral artery ...

The ems muscle stimulator can relief of pain associated ... [Pocket size but huge power] - This electric tens machine built with a powerful lithium battery for 30 hours of continuous therapy.

That is handled by a series of electrodes on the forearm which stimulate the finger muscles using Electrical Muscle Stimulation (EMS), hence the name. The problem with EMS for manipulating fingers ...