Information in Arabic?! Leather with a dedicated lock for installation between the nozzles and the nozzle connection that is installed in the engine to prevent oil leakage during engine operation. Some of our customers have reported issues with slight leakage between the manifold/pipe section on their DDM Dominator® Pipe. We are now using a super-heavy duty high temp silicone tubing. The coupling consists of simply a piece of high temp silicone tubing, and a hose clamp. Simply slide on the tube, clamp it tight, and any leaking issues you have had will be a thing of the past. Approximately 19mm ID and 27mm OD