Dosimeters perform monitoring and measurement of ambient dose equivalent and ambient dose equivalent rate in the wide energy range - from the natural background level up to 5-10 Sv/h (500-1000 R/h). Instruments have two thresholds in DER and DE ranges and non-volatile memory for data storage. Hermetic, water-resistant and shockproof case and the fluorescent backlight on LCD screen allow to use instruments in harsh and extreme conditions. PM1603A and PM1603B dosimeters are recommended for emergency services, customs and border patrol, radiological and radioisotope laboratories, medical professionals, personnel of nuclear facilities, civil defense, fire secure and police.