Welcome back to the late 60's. Snuff-or-Not were great little devices that allowed you to change your exhaust note. Like a quick change exhaust kit. You could make it loud or quite. Twist... It's open! Twist... It's closed! They worked great for a while, but eventually they would wear through the pin at the end and everything would fall out your exhaust pipe. I lost one of mine. But you could not beat the price. I don't think they are made anymore.
They were made by Pacifico, Inc, P. O. Box 398, Portland, Oregon 97207, USA. They were available in 2 sizes. S-25 and S-50. You often saw them on Honda 305 Scramblers CL77, but I had them on my 1970 Harley Davidson Ironhead Sportster XLCH.