Ametric 25B20 Inch ANSI 25-1 Hub Steel Sprocket, For #25 Single Strand Chain with, 1/4" Pitch, 1/8" Roller Width, 0.130" Roller Diameter, 0.114" Single Tooth Width (B1), 0.114" Sprocket Tooth Face Width (B1), 1.673 Inch Outside Diameter (Approximate) (de), 1 1/4 Inch Hub Diameter (dn), 5/16 Inch approximate Pilot hole / bore +/- 1/16 inch (d1) , 9/16 Inch Total Width (A), 020 Teeth,(Mfg Code 1-084)