The title is sprocket spelled backwards.
Why? I will tell you why. A rear sprocket erodes much more slowly than a front sprocket, because it has about three times as many teeth to share the wear.
Consequently, it makes sense to replace the rear sprocket only every second time you replace the chain and front sprocket, which should be replaced at the same time to prevent rapid wear of the new part by the old one which has developed different measurements.
Here is the clever part: the first and third and fifth time you replace the chain and front sprocket, reverse the rear sprocket, and add five washers inside it, to make up for the slight asymmetry -- you will understand at once when you see the dishing of one side of the rear sprocket.
I have done this at 22000 miles and again at 66000 miles with my second rear sprocket. In my experience, at 80000 miles now, this process did not cause rapid wear of the chain or front sprocket. The only difference is that I saved the price of two rear sprockets, which is several tanks of gasoline, even at today's prices.
So, kmsz1969, your lovely new sprocket can last about 76000 kilometers,
perhaps twice as far as you expected it to last. But I bet the manufacturer's name is not on the other side of it!