text: "ksi" is the abbreviate of 1000 pounds per square inch, used when psi (pounds per square inch) uses very large numbers.  With regard to metals, it's usually used to express material allowables (allowable stresses), like tension yield strength, FTY.\n\n"MSI" is millions of pounds per square inch.  With regard to metals, it's usually used to express material stiffness like Young's modulus, E.