[en] In 2005, the Laboratoire national de metrologie et essais- Laboratoire national Henri becquerel (L.N.E.- L.N.H.B.) and the Physikalisch-technische bundesanstalt (P.T.B.) each submitted a sample of known activity of ²⁰¹Tl to the International reference system (S.I.R.). In 2006, the National physical laboratory (N.P.L.) submitted their first sample. The range of values of the activity submitted was between 2 MBq and 63 MBq. These key comparison results have been included in the re-evaluated key comparison reference value and replaced the previous results for france and Germany in the matrix of degrees of equivalence in the key comparison database that now contains seven results, identifier B.I.P.M..R.I.(2)-KI.Tl-201. (authors)