This is the genuine Pro-Ject replacement counterweight for the RPM 1 Carbon tonearm, identified by part code 082. Weighing 115g, it is designed specifically to balance the 8.6" carbon fibre tonearm fitted as standard to the Pro-Ject RPM 1 Carbon turntable.
The counterweight slides onto the rear of the tonearm tube and is locked in position with a grub screw. Once set, it allows you to dial in the correct vertical tracking force (VTF) for your cartridge using the calibrated anti-skating and tracking force dial on the tonearm.
If your original counterweight has been lost or damaged, or if you are upgrading to a cartridge that requires a different mass balance, this is the correct replacement part for the RPM 1 Carbon.