VicksVisc was a company that manufactured casings for holoprojectors. They were used on the R2-series of astromech droids, namely R2-D2.
Behind the scenes
The company was named for Vickers Viscount, the airplane from which a reading lamp was used for the holoprojector casing.
Sources
Building a Complete Visual Dictionary on StarWars.com (original site is defunct)
Episode IV Visual Guide — Chapter 6: Lost in the Desert on StarWars.com (original site is defunct)