 Commercially made radiation meters are typically based on electronic circuitry or require a battery-powered charging apparatus, allowing susceptibility to battery shortages and to electromagnetic pulse.The Kearny fallout meter was designed to utilize static electricity, produced by (for example) a hard plastic rubbed on dry paper.The KFM was also designed to be less expensive to build than the purchase price of dosimeters and to be made out of commonly available materials, such that they could be constructed even after a disaster.