Tetraethylammonium chloride
Tetraethylammonium chloride (TEAC) is a quaternary ammonium compound with the chemical formula [(CH3CH2)4N]Cl, sometimes written as [NEt4]Cl, where Et stands for ethyl. In appearance, it is a hygroscopic, colorless, crystalline solid.
Source: Wikipedia — Tetraethylammonium chloride (CC BY-SA 4.0)