Automakers actually manufacture only a few of the parts that go into their cars. More often than not, specialized manufacturers will design and produce parts that end up being used by the automaker. These companies are known as OE Suppliers, and it is their job to manufacture parts for automakers to use in their factories when their vehicles are assembled. It is perfectly acceptable to use reproduction parts, but nothing compares to the original equipment part when it comes to restoring your car to showroom condition. The most famous and ubiquitous OE suppliers include companies like VDO/Seimens, Gates, and Monroe.
The safety of you, your passengers, and other drivers on the road depends on how well your ABS sensors prevent lockups and skids when braking.