The Texas rockers have used the same tone formula for decades, but when it comes to gear and making a statement, they’re kings of style.

Hill’s bass goes from his Shure wireless system into an amp splitter, into Marshall JMP-1s and Valvestate Pro 120/120s, into a DI. He uses two only two effects: An Electro-Harmonix Micro POG Polyphonic Octave and a Micro Thumpinator to filter every note below B flat. Hill’s rig uses 3 channels: clean DI, an octave down DI, and a dirty amp channel.

ZZ Top’s guitar and bass tech, Elwood Francis, explains the ins and outs of the newest guitars and basses that Billy Gibbons and Dusty Hill have out on the road for 2015.