BOSS NF-1 Noise Gate Serial No. 9700, manufactured in Japan around August 1980 This is a method to reduce noise levels by adjusting the threshold and attenuation level of the output level with the SENS and DECAY controls. I used to put it at the end of my effects chain when I was using a lot of effectors in the mid-80s, but I took it off after I stopped using an effects board. An extreme use case is what's known as gate echo. It's not the same as applying it on a mixing console, but if you apply a lot of reverb to an instrument sound and then use the noise gate strongly, you can get the effect of cutting off the reverb sound sharply when it starts to decay. It's not an effector that changes the tone, so it's hard to tell if it's working, but I confirmed that it's functionally working during the power-on check. - Model: NF-1 - Brand: BOSS - Type: Noise Gate - Controls: SENS, DECAY - Input/Output Terminals: INPUT, OUTPUT Thank you for viewing.