How in heck does this work

[toadfrog]

Ran on to this thing while looking for tackle the disabled can use . Vaguley remember something like it . Can somebody tell me how it works .
http://www.ebay.com/itm/ERCOA-3000-...921?pt=LH_DefaultDomain_0&hash=item5405b9a359

 

[Ron Don]

Huh. Fire up the generator!

 

[JSC]

Have not seen anything on them for years ... Do not know a thing about them ..