Tetrodotoxin (TTX) is a highly potent neurotoxin that blocks the action potential by selectively binding to voltage-gated sodium channels (Na v). The skeletal muscle Na v (Na v1. 4) channels in most pufferfish species and certain North American garter snakes are resistant to TTX. whereas in most mammals they are TTX-sensitive. https://www.roneverhart.com/Echo-Fix-EF-P2-Spring-Reverb-Pedal-p32083/