Opatch for 10g to 11g upgrade on Windows

Dear Experts,

I'm going through an Oracle upgrade from 10.2.0.4 to 11.2.0.3.

I have installed the Oracle software 11G  and now I need to apply the SAP Bundle Patch 4.1.2  Installing Required Patches (according to the oracle upgrade guide)  but  I'm unable to find OPATCH or MOPATCH files in  patch files i downloaded from Market Place.

Where can i download this Opatch Utility from ?

Regards,

Domnic.