The Siemens 6ES7841-0CC05-0YA5 is a SIMATIC S7-PLCSIM V5.4 engineering software package. It comes with a floating license for one user, including software and documentation on CD and a license key on a USB flash drive. This software supports STEP 7 V5.4 SP4/SP5 or STEP 7 V5.5 (with or without SP1) and is compatible with Windows XP Professional and Windows 7 Professional/Ultimate. It is classified as a Class A product, meaning it is a standard stock item that can be returned within the specified guidelines.