Park GSC-1 Gear Clean Brush Review
The GSC-1 is a brush made for cleaning your gears and drivetrain. It has a stiff-bristle brush to get rid of loose dirt and grit, and it has a serrated "claw" end that cleans between cogs on your cassette.
Pros: The "claw" end that goes between cassette cogs is great. It's much easier than swiping a rag between each one.
Cons: Even though it's made by Park, it's composed of plastic and metal pieces stuck together, so durability is an issue. The bristle end actually fell right off of the end of my brush (it slides back on though.)
The Final Word
This is worth buying (it's only $3) just for the "claw" end. Use the brush, too, and if it falls off, just use some super glue and put it back together.