The "Adel" clamp is more properly called the MS21919 aircraft clamp. The company named Adel built a good chunk of the MS21919 terminal blocks in the 1960's since then The term has become somewhat associated with these devices despite the fact that they are now made by dozens of companies. The complete description of these terminals follows convention MS21919WXXZZ where: W = "wedge" feature in the cushion which helps prevent small wires from escaping from the cushion. The characters CH have the following meaning: CH = Corrosion resistant steel strap, silicone cushion (205C) Silicone - for use at elevated temperatures in phosphate ester fluids and other areas contaminated by synthetic fluids. Insensitive to ozone. Not resistant to petroleum-based fluids. The color must be natural white.