Acid Brush 3/8 in. Bx Of 144.Features. Safety Goggles or full face shields worn over safety glasses with side shields must be worn by all operators and others in the area of power brush operations Appropriate protective clothing and equipment must be used where there is a possibility of injury that can be prevented by such clothing or equipment Keep all machine guards in place Observe all speed restrictions indicated on brushes, containers, labels or printed pertinent literature.. MSFS, Maximum Safe Free Speed should not be exceeded under any circumstance.