Quattro 4-in-1 Analgesia SystemFour test systems Electronic von Frey Plethysmometer Randall Selitto Grip Strength Meter This special package offers four tests, including Electronic von Frey, Plethysmometer, Randall Selitto meters and the Grip Strength Meter. You get all four test modules and the electronic controller that is interchangeable with all four systems. The electronic controller has up to three inputs, so you can perform up to four unique tests with only one electronic