  We present two simultaneous NICER and NuSTAR observations of the
ultra-compact X-ray binary (UCXB) candidate SLX 1735-269 while the source was
in two different spectral states. Using various reflection modeling techniques,
we find that xillverCO, a model used for fitting X-ray spectra of UCXBs with
high carbon and oxygen abundances is an improvement over relxill or relxillns,
which instead contains solar-like chemical abundances. This provides indirect
evidence in support of the source being ultra-compact. We also use this
reflection model to get a preliminary measurement of the inclination of the
system, $i = 57^{+23}_{-7}$ degrees. This is consistent with our timing
analysis, where a lack of eclipses indicates an inclination of $i<80^{\circ}$.
The timing analysis is otherwise inconclusive, and we can not confidently
measure the orbital period of the system.
