  We describe ten strong lensing galaxy clusters of redshift 0.26-0.56 that
were found in the Sloan Digital Sky Survey. We present measurements of
richness, mass and velocity dispersion for the clusters. We find that in order
to use the mass-richness relation from Johnston et al. (2007), which was
established at mean redshift of 0.25, it is necessary to scale measured
richness values up by 1.47. We also present measurements of Einstein radius,
mass and velocity dispersion for the lensing systems. The Einstein radii are
all relatively small, between 5.4-13 arcseconds. Finally we consider if there
is evidence that our clusters are more concentrated than standard cosmology
would predict. We find that six of our clusters do not show evidence of
overconcentration, while four of our clusters do. We note a correlation between
overconcentration and mass, as the four clusters showing evidence of
overconcentration are all lower-mass clusters.
