The SOS 17 ’DS-1 Ultra’ pack contains 80 captures of the Boss DS-1 Keeley Ultra Mod in each of the ToneX, NAM Standard and NAM Nano formats. (Full details above.)
 
Here's what Boss say about the DS-1: 
 
'The DS-1 Distortion is a true icon in the world of guitar effects. Introduced in 1978, BOSS’s first distortion pedal defined a bold new sound, delivering hard-edged attack and smooth sustain that’s been a staple of players for generations. The DS-1 is the top-selling BOSS compact pedal ever, and its original, unchanged design continues to inspire the creation of great music everywhere. The classic DS-1 tone is behind the signature sounds of numerous rock legends, and is ready to fuel your own signature sound today.'
 
The Keeley Mod has two different modes: the Seeing Eye mode and the Ultra mode. Both modes offer increased definition and gain to help give you the 'Wall of Marshalls' tone with the Ultra mode being the fatter, more robust of the two - perfect for beefing up strats or for pushing amps hard.
 
For both the Seeing Eye and Ultra modes, there are 9 gain settings with 6 different tone settings for each. 
 
Stomped on by the likes of Josh Klinghoffer, OZ Noy and Bobby Hambel.