The case comes with a belt loop which should eliminate any possibility that the dosimeter could be lost. Nevertheless, this example also came with a cord that could be tied to the clothing. As it was explained to me, there was no excuse for a lost dosimeter, even if the sailor went overboard. Apparently the belt loops were broken often enough that some users employed the cord as insurance.

Each dosimeter consists of two CaF 2 :Mn elements encased in a glass bulb. The heating element is a metal strip that is sandwiched between the elements - the elements are held in place by a metal spring (see bottom photo). When a current is applied, the CaF 2 :Mn is heated.