The MD-1 is a respirator designed to be used by children aged 6-15 years old. The mask is available in three sizes, small, medium & large. Produced in former Yugoslavia by Miloje Zakić, the company changed its name to TRAYAL Korporacija (TRAYAL Corporation) and still manufactures the MD-1 at their factory in Kruševac, Serbia.  The shelf life of an MD-1 kit is 10 years.