Original Cannondale Hollowgram spider lockring install/removal tool. This shop-quality tool is required to remove or install the lockring that keeps the spider securely fastened to the drive-side crankarm. This version 2 is thinner and has a better interface for putting a big wrench on it for leverage.
Tool has both interfaces for a socket wrench (recommended) or a large adjustable wrench.
The lockring was installed originally with tough Loctite, so having the right tool is critical. Be sure to clean off the old and install new Loctite before reinstalling the lockring.