Bosch AL559N New Alternator 100% new premium quality components, including major heat related/wear items: rectifier, regulator, rotor, stator and bearings withstand excessive heat and high electrical demands. Bosch Professional Preferred 100% New Alternators are 100% full-loaded tested to meet or exceed original equipment manufacturers' amperage and voltage output standards for proven charging performance. No other original equipment alternator or starter manufacturer charges as many batteries as Bosch in the Nextel Cup Series because the Bosch Professional Preferred 100% New Alternators provide more power under extreme, high-demand conditions. 100% full-load tested for proven starting/charging performance