Marshall Horizon Indicator ONLY for 7" and 6.5" Marshall monitors models: 651STX and 70XP and 70XHB series (this includes the Steadicam-branded version.) For monitors with firmware version 3.40 or higher.
This artificial horizon indicator overlays X and Y leveling scales on your monitor screen.
A great alternative to a bubble level. It is not motion-compensated, but still is still very useful in the field, and as a training aid. Excellent condition.
B&H price: $245
My price: $145 including via USPS (international shipping extra)
If you want, I will throw in a sturdy metal clamp that can be used on the bottom monitor tube of Zephyr, Scout, and Pilot.