Sentinel X100 & X400 Pack - Inhibitor & System Restorer Sentinel X100 & X400 Pack X100 1Ltr - Heavy duty inhibitor. Enhanced scale & corrosion protection. For all system metals. Ensures optimum boiler efficiency. X400 1Ltr - Can be used in all systems. Prepares existing systems for the installation of new boilers, pumps or panels. Does not cause pin-holing or leaks. This product is subject to specific safety warnings - in case of contact with eyes, rinse immediately with plenty of water and seek medical advice. Avoid contact with skin. Avoid contact with eyes. Specialist trade product