Death Metal distortion pedal by Digitech. For electric guitars but could be used with electric bases too. It's a high quality distortion pedal with the gain set to 11 all the time.
Set the level to adjust the output volume then colour the distortion with the 3-band EQ. Best kept with all 3 EQ knobs at 12 o'clock but works well to boost and cut by 1 or 2 o'clock-positions if you want to cut through into specific tonal spaces to stand out from the other instruments in the band.
All metal case can take some serious punishment so is great for on-stage use. Perfect for heavy metal (obviously best for death and black metal). Has 2 output jacks; one that goes straight to the amp and one that goes to a mixer (I believe this one is a "line out" which bypasses the built in EQ). Powered by regular 9V battery or by a center-negative 9V DC power supply like 99% of guitar pedals that don't need proprietary power connectors.