Fit for Hot Tub Parts: The O-ring 711-4030B, a 2-inch spa hot tub heater gasket, is compatible with Gecko, Hydro Quip, Aeware, United, and most other Flow-Thru components. Designed for a 2-inch pipeline (actual measured outer diameter is approximately 3 inches). Compatible with most spa pump or heater union gaskets, including Arctic Spa, Self-Flowing Spa, Beachcomber Spa, Bullfrog Spa, Volcano Spa, California Spa, Canadian Spa Company, Filbur Spa, Coleman Spa, Catalina Spa, Jacuzzi, Hot Spring Spa, Marquis Spa, Sweetwater Spa, Thermospa, Unicel Spa, Viking Spa, Vita Spa, and Waterway Spa. Suitable for most spa pumps, hot tubs, and heater joints to prevent leaks. High Quality Replacement: This 2-inch spa hot tub heater gasket is made from high-quality rubber and manufactured to strict quality control standards, meeting or exceeding part specifications. Easy to Install: A direct drop-in replacement for spa heater union gaskets. Designed for quick and simple installation at the heater-to-pump connection to ensure a secure, leak-resistant seal. Color: As shown in photo Material: Rubber Package Contents: 4 x Spa Hot Tub Heater Gasket Note: Slight color variation may occur due to lighting and screen settings. Measurement tolerance is ±1–3 cm.