Fresh milk should always be strained through a new filter disk before cooling. Never reuse filters. High-quality non-gauze filter disks allow faster milk flow, remove more fine sediment, and give more uniform filtering than gauze-faced disks. These filters fit our 4 qt. strainers. Actually "in-line" filters for a pipeline setup, they're slightly thicker than other filters; they work well. Box contains 200 disks.