This tool is mandatory if you work on differentials regularly as it allows you to remove the bearings without damaging the bearings. This saves you money by you reusing the side bearings instead of destroying with some 2 or 3 jaw bearing puller. This tool works in conjunction with your 1/2" impact gun and it is mandatory that the bearing race is used when pulling the bearings! Replacement parts are available if you wear items out over time also!