The ToupTek Astro focal plane tilting adapter (tilter) mounts on ToupTek Astro's ATR series of cool-frame cameras. It allows fine adjustment of the camera tilt angle to correct for minor deviations from the optical axis. It features a T2 thread and retains the camera's original 17.5mm backfocus.
The advantage is that it is adjustable from the rear, which means that even when assembled with a filter changer, filter drawer, etc., the adjustment screws remain accessible.