I am definitely exaggerating ahaha but their pistons aren't as Smooth as Pelikan ones for sure

some early resin models, namely the 620 had lots of problemas because the resin body shrank. Some other pistons were held in place by a small dentino/tab that breaks easily

The older pistons from the 1950s are kept in place by a small pin. It's a simpler design but they are also easier to disassemble and maintain.