Heavy Duty Pool Filter O Ring Replacement for 21 Inch Sta Rite System 3 Pools and Spas Fits DE SD S7D75 S7M120 S7M400 S7MD60 S7MD72 S7S50 Filters Airtight Seal Long Lasting Rubber Ring 24850-0008 O-485

Single 21 inch pool filter O-ring for System 3
✔️ Fits 21 inch System 3 tanks; 24850-0008 compatible

This heavy-duty O-ring replacement delivers a tight, airtight seal for 21-inch filter tanks found in many pools and spas. It’s designed to withstand chlorine and salt environments and is a common fit for 21-inch System 3 modular tanks and compatible DE and cartridge filters.

✅ ID 21.2 in, OD 22.36 in, CS 0.57 in
✅ Heavy-duty rubber resists chlorine and salt damage
✅ Airtight seal prevents leaks and ensures proper filtration
✅ Compatible with 24850-0008, 248500008, O-485 and similar 21 in filter setups

💡 What is a pool filter O-ring used for and why replace it?

Replacing the O-ring keeps the system airtight and reduces water loss and pressure drop.

• handy for 21-inch filter tanks and standard DE or cartridge setups
• durable rubber with chlorine and salt resistance
• easy to install with PTFE-based lubricant for best seal
• long-lasting replacement that helps prevent leaks