Martin's standard duty wing pulleys are constructed from extremely heavy materials and are recognized in the industry as the most aggressive CEMA grade stock pulley on the shelf. All Martin wing pulleys utilize the unique 'end-pipe' design, which offers ultimate protection against wing folding and hub-weld fatigue. Our minimum 3/8 in thick contact bar yields additional life in abrasive applications where our competitors thinner bar does not. Additionally, our 1/4 in thick wing offers greater structural support in aggressive applications. Martin Wing Pulley, Standard Duty, M-HE40 Bushing, 20 in OD, 51 in Face Width, 4 in Shaft Diameter, Crown Face Profile, Steel