Opened box, never used.

The SGI is a high performance line driver system for guitars that takes an unbalanced instrument signal and allows you to drive it as far as 100 meters (300ft) without noise.

This includes both sides: RX and TX (which are often sold separately).

The SGI is for when you want all the tone your amp can produce, but need the amp in an isolation booth, or offstage. If you play in rooms where stage noise has to be low, but you need all the tone your amp gives you at louder volumes, then you need the SGI. It's a life saver in church contexts, or basically any place you might encounter a sound engineer saying "turn it down".