HEAVY DUTY FLAT IDLER, part number: 280156. 

Includes 3/8" ID reducer bushing.

V: 1 1/4" , Height: 1 1/4 ", OD: 3 1/4 ", Material: Steel , ID: 1/2 "

Bunton: PAL0368A,
Hahn: 280156,
Jacobsen: 317726,
John Deere: PT8649,
Massey Ferguson: 1024515M1,
Murray: 21409, 21409MA,
Noma: 300920, 40223,