This is a 25.4mm X 50.8mm (1" X 2") block that is 6.35mm (1/4" thick. It has a 19.05mm (3/4") diameter pass through hole and 19.05mm (3/4") font size F with a recess depth of 3.175 (1/8").
The purpose of the block is to check the dimensional accuracy of you printer, including the level of the bed (check for same thickness at all four corners).
It took my fabtotum roughly 30 minutes print time.