A family/clan tartan according to The Register of Scottish Tartans. However, it is one of the most used tartans for a lot of things, including off-the-peg kilts, ladies' kilted skirts, furniture decoration etc.
The kilt is a 5.4 yard lightweight wool casual made by O'Neil of Dublin. The quality is good. Some retailers, like Irish Shop in Berlin. are selling them. Or you can order directly from O-Neil of Dublin.