  Galaxy cluster masses help to constrain cosmological parameters through the
halo mass function. To get rid of major biases in the mass measurement, we
directly probe the cluster gravitational potentials by observing their
gravitational lensing on the Cosmic Microwave Background (CMB). We measured the
average mass of a 468-cluster sample using SPT-SZ and Planck/HFI PR2 sky maps
and compared it with the masses provided in the SPT-SZ data set. We found an
average mass ratio of $M_{\rm CMBlens}/M_{\rm SZ} = 0.98 \pm 0.19$ (stat.) $\pm
0.03$ (syst.) [arxiv:2402.18346], in agreement with SPT-SZ masses. We also
showed that the CMB large scales are important for the reconstruction of the
lensing potential of a cluster with a quadratic estimator.
