This Woolly Mammoth was made with a sample Sylvia Massy enclosure and large, round tuna can 2N2219 silicon NPN transistors (similar package to our stock Fuzz Factory 2N404). To our ears, they have a little more gain on tap than 2N3904 transistors (which are usually used in the Woolly circuit). We were trying out some different ones for the limited edition Massy pedal. You get to purchase one of the experiments.