A new experimental result out of KATRIN has cut the upper limit of the mass of electron neutrino by half, to 1.1 eV. This was reported at the recent conference and in a recent preprint.
I suppose if I want to be accurate, I should say it is the electron antineutrino, since they measured this from beta decays, but nowadays, we don't have a clear cut idea of the difference between the neutrino and its antiparticle. For all we know, they can possibly also be a Majorana particle.
I'll be giving this report to my students in the general physics class, and see if they can convert the 1.1 eV into "kg". :)