The nut holding the drive sprocket on your oil pump can become loose over time. We have personally seen this on more than a couple M3 motors, but caught the problem before the nut became too loose. Others have not had such luck.
There are countless stories of oil pump nuts coming loose and causing a no oil pressure situation costing thousands in repairs or replacement.
This oil pump nut has a hole EDM'd (Electrical Discharge Machined) on the flat to allow it to be safety wired to the oil pump sprocket.
The kit includes one oil pump nut and a longer than needed length of safety wire to secure it. It's a small price to pay for piece of mind.