This is a Sioux Chief Mini-Rester Water Hammer Arrester (660-TR1) used to stop banging pipes by utilizing a pressurized cushion of air to absorb the water pressure spike. It is primarily used to prevent pressure spikes in the water lines of dishwashers and other compatible appliances. It has 3/8" compression fittings on both ends.
The Sioux Chief 660-TR1 Water Hammer Arrester uses a compression tee connection and dual o-ring piston to separate the air cushion from the water system to ensure permanent protection from waterlogging.
This water hammer Arrester can be installed vertically, horizontally, or any angle in between. No access panels are required to use this part. It was manufactured in the USA and is also known by part number 660TR1.