Apollo DCDA-4SG Double Check Detector Assembly is engineered to safeguard potable water supplies from contamination due to back-siphonage or backpressure from non-health hazard substances, making it ideal for fire protection systems and applications requiring low-flow detection and robust backflow prevention. Available in sizes from 2-1/2" to 8" (replacing Model 4S-600, except for 10" size), it features a domestic stainless steel body for 2-1/2" to 8" models and FDA-approved epoxy-coated ductile iron for 10" and 12" models, ensuring corrosion resistance and durability.