{"product_id":"3900-chain-tensioner-kit","title":"Polaris Genuine OEM 3900 Chain Tensioner Kit","description":"\u003cp\u003eThis is the genuine Polaris chain tensioner kit, part number 39-120, for the 3900 Sport pool cleaner.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat the tensioner does\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eThe 3900 drives its wheels through a chain, and the tensioner keeps the slack out of that chain. Once it wears, the chain can skip a tooth under load. The cleaner then loses drive on one side, wanders away from its pattern, or gives up on wall climbs it used to manage. Replacing the tensioner is the fix, and it is usually done at the same time as any other drive train work.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003ePart numbers\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eThe kit is listed as Polaris 39-120, and the product data also notes 393-121 molded into the sprocket. Both numbers are recorded here so you can match whichever one is on the parts you took out.\u003c\/p\u003e","brand":"Zodiac","offers":[{"title":"Default Title","offer_id":48633641500884,"sku":"POL-201-4907","price":40.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0801\/9568\/2516\/files\/default_494b2eda-dee3-41a5-8134-5edf69da28e5.jpg?v=1788808096","url":"https:\/\/www.activepoolsupply.com\/products\/3900-chain-tensioner-kit","provider":"Active Pool Supply","version":"1.0","type":"link"}