1. Boss Metal Zone: This is a budget-friendly distortion pedal known for its high gain and versatility. It allows you to shape your sound with a three-band EQ and adjust the distortion level.
2. MXR Distortion+: This vintage distortion pedal offers a classic rock sound with its smooth and warm distortion. Metallica used it in the early days and it's still popular among guitarists seeking a vintage tone.
3. ProCo Rat: The ProCo Rat is known for its thick, saturated distortion. Metallica used it for their rhythm guitar during their thrash metal era.
4. Ibanez Tube Screamer: This overdrive pedal is popular for its mid-range boost and natural tube-like distortion. Metallica has used it for solos and to enhance their overall distortion sound.
5. Line 6 Spider: Metallica used the Line 6 Spider distortion pedal in the late 90s. It provides various distortion models and amp simulations.
It's worth noting that Metallica's distortion sound comes not only from pedals, but also from their signature guitar setups, amplifiers, and recording techniques.