It's one knob, but it's an overdrive rather than a boost. The Cranker is basically designed to act like another tube in your preamp stage, so it warms things up and adds some gain and output, without changing the overall vibe too much. It does a great job.

Model: EarthQuaker Devices Speaker Cranker
Made: Akron OH USA, 3 June 2019
Serial: 2635
Type: overdrive
Power Input: standard 9v DC centre-negative (supply not included)
Accessories: none

Condition notes: used, no major marks. Tested and fully functional.
Overall: very good condition (8/10)