These are Hewlett-Packard 557-216
Fan Shield . Fan Grill . Finger Guard Protection

Dimensions

125mm / 4.92 Inch Area Diameter = 5 Inch
163mm diagonally between screw mount holes

These fan shields were previously owned by Hewlett-Packard Agilent Keysight and were purchased in 2004. They have been in store stock at Luddite Electronics in Longmont Colorado and sold here.