Getaprop american turbine http://www.getaprop.com/ Sat, 4 Feb 2012 14:20:36 -0600 en Aluminum Impeller... Size AT-C If your engine turns more than 5500 RPM or if you operate in a very rocky or abrasive environment, then the stainless steel impeller should be your choice. http://www.getaprop.com/content-product_info/product_id-1878/american_turbine.html http://www.getaprop.com/images/products/impeller[1].jpg http://www.getaprop.com/content-product_info/product_id-1878/american_turbine.html