It's for Bass I swear. In order it's a tuner, Bass Balls, a Boss Compression Sustainer, a Morely Power Wah Boost, Big Muff, Route 66 Overdrive Compression, and finally a MXR smartgate :
Cliff Burton bass sound | TalkBass.com
How Scott Pingel Took Cliff Burton's 'Anesthesia' to the Symphony
The Many Bass Guitars Of Cliff Burton – FuelRocks
Morley Announces Cliff Burton Tribute Series Power Fuzz Wah Pedal – No Treble
Alembic Club: This bass player uses this effects (and amps)
Morley PFW Cliff Burton Tribute vs. Original Tel Ray Wah | Page 5 | TalkBass.com
Cliff Burton | Equipboard
CliffBurtonDay - 5 Essential Pieces of Gear – t.blog