simplcut is an extension of the simpl model designed to work with a cutoff and a physical Comptonization kernel.  The Comptonization setting is based on nthcomp.  The model parameters are given below.
1.  Gamma   (spectral index)
2.  fsc    (scattered fraction)
3.  ReflFrac     (Reflection Fraction.  Negative values omit the transmitted portion and return just the scattered spectrum.)
4.  Energy Turnover     (Exponential cutoff Ecut when negative, kTe from nthcomp when positive)
simplcut can be compiled expeditiously using “xspec – go” from the command line in the installation directory.   Note that like simpl before it, one should use “energies” when using simplcut.  (I.e., “energies 0.001 1000. 1000 log”.)  A tarball of the package is provided below.