The black Kaweco steel spring is DLC coated. The "Diamond like Carbon" coating is extremely durable and can withstand the stresses of everyday use of a pen fountain pen. A welded-on iridium grain at the tip and a precisely measured spring slot minimize the tolerances.
All Kaweco fountain pen nibs are made exclusively in Germany
Note: This spring fits all fountain pens of the following Kaweco series: AL Sport, AC Sport, Liliput, Student, and Dia2.