Kraus Cartridge Seal Head Driver Tool The Kraus Cartridge Seal Head Driver Tool is essential for Ohlins fork rebuilding and cartridge installation, specifically designed for use with Ohlins FKS 508 cartridges. Features: Uses a 3/8 drive Provides easier assembly and disassembly when servicing specific Ohlins forks Designed and engineered to be used with the KRT Forks (Ff52X), Dynamoto Forks (Fgrt 205s), and FKS 508s