The large round crystal shows off the workings of the watch - the tubes, battery, high-voltage power supply and setting controls are all visible.
The watch features 12 or 24-hour time display mode, user-settable tilt angle, and easy time setting operation. The timekeeping rate is adjustable to permit regulation to within a few seconds a week.
The two Nixie tubes are the widely available B-5870 type and are socketed for easy replacement in case of damage. (They have been known to develop short circuits between adjacent cathode plates as a result of mechanical shock.) These tubes have 0.6" (15mm) tall digits for easy reading in adverse conditions.
Opening the case by unscrewing the ribbed cover reveals the time setting buttons, the battery and the tubes. The battery lasts several months, and is avilable at any drugstore.
For the hardcore code tweaker, a programming adapter allows the GPL'd PIC firmware running the watch to be hacked up at will. The source code is available on the firmware page.
The case is made of strong, lightweight aircraft aluminum, hard anodized for lasting beauty. The rear of the case is gently contoured for comfort in all-day use. An O-ring seal keeps out water, dust and dirt. The strap is a standard 20mm size, available at any fine jeweler.