The solid scintillator CsI (Tl) is a high sensitivity radioactivity detector  in spite of small size which compared with the GM counter or the ion chamber.

Using with many units can lead to observing the level of wide regional environmental gamma-ray dose.  and It is possible to manage automatically the data through the Internet.
Indoor and outdoor, area, space dosimetry distribution of such prefectures obtained when using　many equipment.

The detection limit of gamma-ray is measured from 0.001μSv/h.