You may think this isn't really important but the spin gear is just as important as any other part, even though you may think it doesn't do anything much. It is very important to consider what to use when you are customizing.

Original Left/Right SG is about 4 grams

Neo SG is about 3.5 grams

Neo SG with MW(Metal weight) is 5 grams

Neo SG with S/N Magne Core is 6 gram

Neo SG with Metal Driger's Heavy Metal Core is 9 grams

Note: Engine gears weigh 11 grams, this is not included in the list becuase it is not customizable with the gears above.