This is an ELK Big Muff Sustainar, a famous Japanese-made FUZZ pedal produced in the 1970s. The TONE knob has a slight catching feel, but it functions without any problems. Also, the screws (for battery replacement) that were on the four holes on both sides are missing. Please consider this item as a vintage product, and agree with the condition shown in the photos and the description before making a purchase. If you have any questions, please feel free to ask. - Model Name: BIG MUFF SUSTAINAR - Brand: ELK GAKKI CO. - Controls: Volume, Sustain, Tone - Internal Structure: Transistor circuit - Exterior Material: Metal case Thank you for looking.