We have a large quantity of Dosimeter Corp Model 866 (1000 mR) and other ranges available for sale. This listing is for 5 units. The Model 866 is a standard instrument that has been extensively used by the nuclear industry for many years and is still used in Emergency Kits at Nuclear Stations for their reliability and ease of use. Unlike electronic dosimeters, no battery is required inside the unit. We have a few battery operated chargers that we can sell for $80 each in addition to these units, or you can buy new ones online. I really like these because they are inexpensive and work very well as compared to electronic dosimeters costing over $400. We will drift test these prior to selling and only sell those that pass the ANSI Standard for drift of 10% of scale over 24 hrs.