Why would they install one of this with a well system for domestic with 40# pressure?
Water Hammer Arrestor
Mini-Trol® shock suppressors are the perfect solution for individual fixtures. The compact design can fit anywhere a washing machine, dishwasher or toilet is installed. The permanently sealed diaphragm will not waterlog like tube-type air chambers.
• Non-Metallic Internals
• Sealed Air Charge
• Easy Installation