#603 OIL TOLERANT RETAINING COMPOUND The LOCTITEA(R) 603 Oil Tolerant Retaining Compound is engineered for bonding cylindrical fitting parts, especially in situations where maintaining consistently clean surfaces is challenging. This compound cures anaerobically-activating in the absence of air-between closely fitting metal surfaces, effectively preventing loosening and leakage caused by shock and vibration. Notably, LOCTITEA(R) 603 exhibits exceptional tolerance to oil and other contaminants, ensuring reliable performance even on surfaces that are not thoroughly cleaned. FNH specifically recommends using this product for attaching rail systems on SCAR 16S/17S rifles, h Mfg: Loctite 50ml.