I have seen a lot of calibration cubes but haven't found one that indicated the axis which can make for some confusion when measuring for accuracy after the part has been moved off the build platform.
This cube has simple marks noted on it to reference which axis might be out of alignment, so you can make minor adjustments to achieve more accurate dimensions in your parts.
Hope you enjoy, and Happy Printing.
Should be orientated for drag and drop use. If not set orientation so cube is resembling proper axis.