| I've used one. It is very dirty, and makes for some strange noises. It is also long out of production, and when you can find it on eBay, which is rarely, it always sells for thousands of dollars. There is a DIY Ring Stinger clone project available. It doesn't come in kit form, sadly, but it does provide everything you need.
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Electro-Harmonix #4, Fretless #44, P-Bass #431, Lefty Union #141, MXR #4, Peavey #13, βΘИΞКЯŲŜĦÏИĞ® #37 | 
