We present a magnitude and size limited survey of edge-on disk galaxies in the Sloan Digital Sky Survey Data Release 7. The objects are classified into several distinct morphological Hubble types using an automated algorithm based upon bulge size and disk thickness. We detect a large fraction of bulgeless galaxies. This is in contrast to current theoretical models of galaxy formation and evolution in which the existence of pure disks cannot be fully explained. We also study the intrinsic thickness of those galaxies and find that a majority of the systems exhibit a red envelope. This feature can be explained as a potential signature of thick disks.