The first filter is a pre-filter that helps remove soap, oil, and other suspended particles before they enter the system. It reduces the need for chemicals such as clarifiers, scum removers, cleaning agents, and defoamers, minimizes filter maintenance, and helps maintain clean water. Easy to Install: Place the hot tub pre-filter on top of the skimmer basket. Secure the filter tab into the existing slot of the MAAX Spas skimmer basket. First filter model number 100497. Easy to Clean: The spa pre-filter can be rinsed as needed. It is recommended to clean it once a week. Replace the filter based on spa usage, typically every three months. Compatibility: This replacement pre-filter is designed for use with spas from MAAX, LA Spas, Cooperage, and Elite Spas. Color: White Material: Chemical Fiber Package Contents: 4 x Pre-Filter Note: Light reflection and different display settings may cause slight variations in color between the image and the actual item. Measurement may vary by +/- 1-3 cm.