RAID levels denote the different ways of storing data in a RAID. Most of the RAID levels allow for the redundancy, with RAID 0 being a notable exception. To recover data from RAID you need to know which RAID level you have.
Sometimes when a large array goes down, you just need more oomph. Or, you may be lucky to have one of the tricky RAID controllers which deviate somewhat from the academic RAID models.
The RAID reconstruction process essentially gives you a set of RAID parameters. The parameters per se are not very useful. Obtaining correct parameters does not guarantee immediate RAID recovery. Typically, some intermediate step is required before the array data can be accessed, involving either a high capacity spare storage, or some interaction with a data recovery software.
Note 1: Requires a blank storage of the same size as the capacity of a failed RAID array. Note 2: Requires an appropriate license for a data recovery software, none of which are free.
In the end of the day, ReclaiMe Free RAID Recovery is cheaper and more capable. Click the link to download ReclaiMe Free RAID Recovery.
If you still want Runtime RAID Reconstructor, download it here.
Please note that the comparison above is valid as the things were in October 2011.