Brimar's EZ Ammonia Pipe Markers are a practical, low cost way to comply with ANSI A13.1-1981 standards and IIAR recommended guidelines, bulletin #114. These guidelines call for the pipe content, and directional flow to be marked at various locations throughout the refrigerant system. The use of Brimar's labeling system will insure your compliance. Each marker comes with an arrow that can be applied in either direction. Brimar's EZ Ammonia Pipe Markers are manufactured with the industries most durable vinyls, inks, and the absolute best acrylic adhesive available. These quality standards insure long life both indoors and outdoors.