HP Product 266199-B21 is compatible in the following HP Models:
HP
Compaq Presario 3900 Desktop PC series
Compaq Evo w4000 series
Compaq Evo D510 series
Compaq Evo D500 series
Compaq Evo D320 series
Compaq Evo D311 series
Compaq Evo D310 series
Compaq Evo D300 series