In this talk I will provide motivation for determining the neutron radius of heavy nuclei, and why PREX II and CREX provide theoretically clean measurements in lead-208 and calcium-48. This will include a description of parity-violating electron scattering experimental design and efforts to minimize the systematic uncertainties. The neutron skin measurement on lead provides information about the neutron matter equation of state at nuclear densities, which is complemented by the measurement on calcium where ab initio nuclear structure calculations can be performed. These measurements are relatively free from strong interaction uncertainties because the electron probe does not interact via the strong force. The results at nuclear densities can be compared to astrophysical measurements of neutron star radii. I will present results for the PREX II experiment, and provide preliminary results from CREX.