Traceability
If you are maintaining manual records, files and photocopies to trace where what was bought, where it was consumed and where it ended up, then read on. An ERP System is designed specifically to solve this type of problem. All the details of your inventory receipt are registered through until it leaves your building.
In many cases, what surprises people are the additional steps required to capture data in order to properly relieve the specific inventory. This view is often falsely compared to the ease of maintaining manual records. If an "apples to apples" comparison took place, then you would probably learn that the manual system is taking considerably more time, without providing the benefit of quickly tracing the inventory.