Tractor-Parts.co proudly carries the following sizes of Idler Sprockets:

40BB17H X 5/8  
40BB17H X ½      
40BB18HX ½       
40BB18H X 5/8  
50BB13H X ½      
50BB13H X 5/8  
50BB15H X ½      
50BB15H X 5/8  
50BB17H X ½      
50BB17H X 5/8  
60BB10H X ½      
60BB10H X 5/8  
60BB11H X ½      
60BB11H X 5/8  
60BB13H X ½      
60BB13H X 5/8  
60BB15H X ½      
60BB15H X 5/8  
80BB12H X ¾      

All with a precision ball bearing that is pressed and secured into the sprocket plate.