These heavy-duty aprons are made exactly like the medium-duty aprons except that the rubberized sheeting is at least 30 percent heavier. The weight specification for the heavy-duty aprons is 10 ounces per square yard. This specification is a reliable indicator of the apron's durability and quality. These durable, chemical-resistant aprons afford excellent protection against chemical spills. Rubberized laboratory aprons are manufactured using synthetic rubber and do not contain latex. These aprons will not cause an allergic reaction in students who are sensitive to latex.