Intrinsically-safe electronic equipment can be used in hazardous atmospheres with dangerous concentrations of flammable gases or dust. Non-intrinsically-safe electronic devices could cause an explosion by creating a spark or excessive heat.
Should I Order an Intrinsically-Safe Minitor VI?
Unless your fire department has a formal intrinsic safety program, you probably should save the $50 and buy the non-intrinsically-safe model. Another way to determine if you need IS is to check your radio for the FM Certification label. If your radio is not IS then your Minitor VI should not need the certification.