Drum unit / Imaging Drum Compatible With HP Q3964A 122A HP122A For: HP Colour LaserJet 2550 HP Colour LaserJet 2550L HP Colour LaserJet 2550Ln HP Colour LaserJet 2550n HP Colour LaserJet 2800 HP Colour LaserJet 2820 HP Colour LaserJet 2840 Page Yield: 20,000 @ 5% Average Coverage Colour: 4 Colour Drum Unit.
eBay