We present a study of the X-ray properties of several NLS1 galaxies , focusing on their warm absorbers .
In the first part , we discuss properties of dusty and dust-free warm absorbers in NLS1s , and study their potential contribution to high-ionization optical iron lines .
In the second part , we summarize our work on the exceptional spectral variability of the NLS1 galaxy RX J0134.3 - 4258 ( from \Gamma \simeq - 4.4 in the ROSAT all-sky survey observation , to \simeq - 2.2 in our subsequent pointed observation ) .