This is a complete replacement kit for the Oster 1200 blender (with the somewhat rarer big base). It comes with one replacement glass jar, one black lid, one clear lid insert, one black (and grey) base, one blade assembly, and two blade gaskets.Note that while everything comes well packaged together, the gaskets were not installed. One must unscrew the base from the glass and insert one of the two included gaskets prior to use. There are no instructions included.In the attached photo I have included a side-by-side comparison with the Oster OEM jar assembly. The replacement jar and assembly is on the left side and the OEM is on the right. Notable differences:* The anti-spin locking pawl on the base is grey plastic rather than black plastic. This does not affect functionality.* The bottom of the glass jar is rough rather than perfectly smooth in the OEM (see top arrow). This may cause premature wear on the gasket and may also cause leaking at the base. I will report if this becomes the case.* The gaskets are a bit undersized for the base and are made from a soft plastic rather than the OEM rubber. Not sure yet if this will cause leaks. I will update the review if it does.On the plus side, the glass jar is thick and well made. The markings on the jar (hard to see in the photo) are actually larger and easier to read than the OEM jar. Except for the unpolished bottom the jar is an exact reproduction of the OEM jar and can be used with the OEM base assembly if needed.The rest of the included components are all interchangeable with their OEM counterparts.I will update the review with performance information in a few weeks.