The Physikalisch-Technische Bundesanstalt (PTB) is the German NMI. PTB performs fundamental research and development work in the field of metrology in the areas concerning the determination of fundamental and natural constants, the realisation, maintenance and dissemination of the legal units of the SI as well as within the framework of legal and industrial metrology. The experts at PTB are world leading in temperature, pressure, and electrical measurements, which has been verified by many international comparisons. Extensive experience and facilities in primary and practical thermometry. This includes the realisation of the International Temperature Scales from 1 mK to the highest temperatures. Noise and dielectric-constant gas thermometry constitute the basis for primary thermometry at PTB.