Because we have a long-term land lease for our facility, we do not want to depreciate any leasehold improvements beyond the practical end of the lease.  As we were recently establishing a useful life for a new building, we wanted to depreciate the building over the exact number of months remaining in the long-term lease, but had to choose the closest year instead.  The change in depreciation was small, but it would make more sense to have an asset depreciable life that exactly matches up with the remaining property lease as currently negotiated.