This is a simple 1.5"x1.5"x0.05" calibration square that i use to check that my first layer calibration is correct. This prints in just 3-4 minutes so it's a quick way to verify that my printer is good to go for larger prints. I generally keep different gcode files of this CalSquare on my printers SD card (one for each type of material that I print) so that I can easily verify any of the different materials before printing. I use this on my Prusa i3 MK3