This introduction to the world of professional orchestral
sounds is the opposite of a "light" version - it is the
largest, broadest collection in the entire Horizon Series.
The feedback from users of our award-winning orchestral
sample libraries was the driving force behind the creation
of Opus 1. It contains handpicked samples and Performance
Elements from the Vienna Symphonic Library's Pro Edition.
Our revolutionary Legato Performance instruments and a
selection of the most important single note articulations
allow for superior arrangements with the best possible
realism.

Opus 1 was designed for convenience. Its logical,
consistent structure is easy to grasp, instruments can be
exchanged without having to figure out altered program
numbers or unexpected controller assignments. If you want
maximum orchestral output with a single computer system,
this is the library of choice! Opus 1 excels at efficiency
economy and unencumbered creativity, while sacrificing
nothing in the realism and expressiveness that the Vienna
Symphonic Library has become famous for.

http://www.vsl.co.at/english/pages/products_%26_shop/horizon_series/opus_1.htm