The AllPoints Foodservice Parts & Supplies 321659 O-ring is designed for water filtration systems, specifically compatible with Everpure models. This durable rubber O-ring features an outer diameter of 4 inches and an inner diameter of 3-7/8 inches, with a thickness of 1/8 inch. Its NSF certification ensures it meets stringent safety and quality standards, making it a reliable choice for maintaining optimal performance in your water filtration system.