X fan 40 x 40 x 20mm dc axial fans 5v12v ballsleeve bearing x fan rdm4020s5 rdm4020s5 is a high quality sleeve bearing 5v dc axial fan from x fan which has been manufactured to a high standard both lightweight and small this brushless cooling fan has passed through stringent quality control testing and has the following safety approvals x fan rdm4020s5 40 x 40 x 20mm axial fan 5v sleeve bearing