What is a heifer cow? A heifer is a mature female cow that has not calved, or given birth to a calf, yet. As soon as a heifer gives birth, she becomes a cow. A cow refers to a female of any age that has given birth.
When most people think about gas masks or respirators, what they usually envision is a tight-fitting plastic or rubber face mask with some sort of filter cartridge. The mask covers the nose and mouth. These are called half-mask air-purifying respirators.
1 Surplus does not necessarily mean âgood dealâ. 2  Not all gas masks are created equal. 3  Youâll probably need a few spare filters. 4  Too late is almost always too late. 5  Paul Bunyan probably wonât make it. 6  You were not born with innate knowledge on using a gas mask. 7  The United States is a big place. 8  Gas masks are a means to an end, not the end themselves.