Four XCS-DR1 clusters that have been classified as silver in Zoo^DR7 (Section 4.1). False colour-composite images are 3 × 3 arcmin with X-ray contours overlaid in blue. Corresponding X-ray images are shown below each optical image (lighter regions show areas of increased X-ray flux). The shape of the xapa-detected extended source ellipses are highlighted in green. The right-most cluster is an example where the classification (as silver) was based predominantly on the X-ray data, the other three are examples where the classification (as silver) was based predominantly on the galaxy overdensity (these three represent the first silver entries in the electronic version of Table 3). From left to right, the clusters are: XMMXCS J004231.6+005119.9 at z= 0.15; XMMXCS J004252.6+004303.1 at z= 0.27; XMMXCS J004333.7+010109.6 at z= 0.20 and XMMXCS J122658.1+333250.9 at z= 0.89.