E-Z LOK EZ-650-10F M10×1.25 solid insert kit

Check compatibility
EZ-650-10F accepts an M10×1.25 fastener while its insert has a 9/16-12 exterior. The suffix F and the labeled pitch distinguish it from EZ-650-10.
Questions before ordering
What does the F suffix identify?
E-Z LOK lists 650-10F for M10×1.25. The corresponding unsuffixed 650-10 kit accepts M10×1.5 even though the insert exterior is also 9/16-12.