UPS - An acronym for uninterruptable power source. A UPS is primarily used as a back up power source for computers and computer networks to insure on-going operation in the event of a power failure. Sophisticated units also have power conditioning and power monitoring features. Wands are older, bar code reading technology but inexpensive and still widely used where speed and performance are not crucial. The keyboard plugs into the wedge and the wedge device plugs into the computer where the keyboard was.
Sophisticated wedges can accept a few different peripheral devices.
Also See Decode.