Water needs to flow through a salt system properly in order for chlorine to enter your pool and keep it healthy and clean. When your Intellichlor® salt system starts to read No Flow when there is clearly water flow, or if it is sensing water flow when your pump is off, its probably time to replace your flow switch. This replacement flow & temperature switch is manufactured by Optimum Pool Technologies and is compatible with any Pentair® Intellichlor® system. We are offering Free Shipping for a limited time on this item!Features: Compatibility: IC15®, IC20®, IC40® & IC60® Pentair® Intellichlor® Salt Systems NOT COMPATIBLE WITH ICHLOR® SYSTEMS Function: Detects water flow as well as temperature Replaces Part Number: 520736 Specifications: Manufacturer: Optimum Pool Technologies, Inc. Model: OPT-520736 3 Wire (Red, White, Black)