Reduction ratios of up to 30:1 are achievable in a single stage. The simple design offers low capital and operating cost. Low headroom requirements make it easy to install. Product sizes may be varied by changing rotor speed and the clearances between rotor breaker bars (also cailedbiow bars or hammers) and apron breaker plates. HSI applications have gone beyond soft and nonabrasive materiais such as limestone, phosphate, gypsum and weath ered shales, to harder minerals thanks to the introduction of alloy steel rotor breaker