The Q138 is a single width panel with the Synthesizers.com Logo printed on it.
It can be used on the back of synthesizer to display the logo during performances or anywhere in the system where a single width blank space exists.
All panels are Moog Unit (MU), are 8.75"";. in height and come in various 'widths'.
A single width panel is 2.125""; - all others are multiples of this single width.