shears are the only option. In Australia blades are more commonly used to shear stud rams. Machine shears Machine shears, known as handpieces, operate in a similar manner to human hair clippers in that a power-driven toothed blade, known as a cutter, is driven back and forth over the surface of a comb and the wool is cut from the animal. The original machine shears were powered by a fixed hand-crank linked to the handpiece by a shaft with only two universal joints, which afforded a very limited range of motion. Later models have more joints to allow easier positioning of the handpiece on the animal. Electric motors on each stand have generally replaced overhead gear for driving the handpieces. The jointed arm is replaced in many instances with a flexible shaft. Smaller motors allowed the production of shears in which the motor is in the handpiece; these are generally not used by professional shearers as the weight of the motor and the heat generated by it becomes bothersome with long use. Animal welfare Animal welfare organizations have raised concerns about the abuse of sheep during shearing, and have advocated against the selling and buying of wool products. Sheep shearers are paid by the number of sheep shorn, not by the hour, and there are no requirements for formal training or accreditation. Because of this it is alleged that speed is prioritised over precision and care of the animal. In 2013, an anonymous shearer reported instances of animal abuse by workers, an allegation to which an Australian Worker's Union representative added that he had witnessed "shearers gouge eyes and break sheep jaws." Australian Wool Innovation insisted that animal welfare was a priority among shearers. The following year, the RSPCA began a cruelty investigation following the release of video footage that PETA said was taken in more than a dozen shearing sheds in New South Wales, Victoria and South Australia. The Guardian reported that the video showed, "sheep being roughly handled, punched in the face and stamped upon. One sheep was beaten with a hammer while another was shown having a deep cut crudely sewn up." The Shearing Contractors Association of Australia "applauded" the investigation, and Wool Producers Australia president Geoff Fisken said the behavior shown in the video was "unacceptable and unsupportable" but that "we're sure it doesn't portray the 99.9% majority of wool shearers – and those shearers would