Material: Housings up to Ø 78 mm made of sintered steel, over Ø 78 mm made of grey cast iron GG20, lever St52, V-belt pulley cast steel. Matching narrow V-belts DIN 2215 und DIN 7753.Pulley with sealed ball bearings, permanently lubricated. Measur A of the pulley can be adjusted by distance-washers on the axis, which is screwd onto the tensioner. Can be used for both tensioning directions.