This alpha source is of open window construction with the source material bonded to the surface of a silver foil mounted in the recess of the plastic disc. This design yields excellent emission of alpha particles without window losses.

Isotope Po210S, 0.1 μCi (3.7 kBq). Half life of 138 days. Alpha source.

Due to the decaying nature of the source, Po210 is not kept in stock but is instead ordered from the manufacturer as required.  Allow around 2 to 3 weeks for availablilty.