A-26 Invader Erection and Maintenance Manual 1945 AN 01-40AJ-2 Copy H-21 The mach number limit is

The mach number limit is displayed at MPH by the red pointer and by the mach number in the inset window at the inside 3 o'clock position

There is a Calibration checklist mounted inside of the felt-lined cherry wood case

The compass body itself is housed within a metal container with gear teeth surrounding the base

published in 1954

But overall

A-26 Invader Erection and Maintenance Manual 1945 AN 01-40AJ-2 Copy H-21 The mach number limit isThis is a 560+ page photocopied Erection and Maintenance Manual for the USAAF Douglas A 26 Attack Bomber in a 3 ring binder. Appears complete, but have not verified every page. Black and white photocopy.