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Silicon spheres are excellent objects that allow both, the realization of the SI unit kilogram derived from the Planck constant and the use as a robust mass artefact. Therefore, the PTB provides three types of spherical artefacts 28Si (primary realization), natSiqp (quasi primary realization), natSisc (industrial mass standard).

For practical use handling, cleaning, and storage are essential in order to guarantee the longterm stability of the artefacts. Documents linked to this webpage give background information of the so called Si-kg approach as well as useful handling information.