{"product_id":"mr-o-ring-343-viton-o-ring-90a-durometer-pack-of-25","title":"Mr O-Ring 343 Viton O-Ring 90A Durometer - Pack of 25","description":"\u003cp\u003eIn this review the Mr O-Ring 343 Viton O-Ring is evaluated for technicians and hobbyists who need a high-temperature, chemical-resistant sealing solution. The bottom line: this pack of 25 delivers consistent, AS568-sized performance with a 90A durometer that resists fuels, oils and heat, making it a practical choice for repair shops, HVAC and fluid-handling systems where compatibility and longevity matter. The review highlights fit, material performance and typical use cases based on the product's specifications.\u003c\/p\u003e\n\u003ch2\u003eKey Features\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Viton FKM construction provides strong resistance to high temperature, ozone and many organic solvents, helping seals last longer in demanding environments.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHardness:\u003c\/strong\u003e The 90A durometer offers a firm cross-section that maintains sealing pressure while resisting extrusion under moderate compression.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSize accuracy:\u003c\/strong\u003e Nominal and actual dimensions are provided so installers can verify fit; precise measurements reduce guesswork during replacement.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eChemical compatibility:\u003c\/strong\u003e Performs well in petroleum products, diesel blends, biodiesel, methanol\/ethanol blends, mineral oils and silicone lubricants, expanding its use across systems.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTemperature range:\u003c\/strong\u003e Rated -26C to 232C (-15F to 450F), making it suitable for high-temperature air and many heated fluid applications.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePack quantity:\u003c\/strong\u003e Supplied in a pack of 25 for maintenance jobs or multiple repairs, helping shops keep common sizes on hand.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2\u003eWho It's For\u003c\/h2\u003e\n\u003cp\u003eThe Mr O-Ring 343 is aimed at mechanics, maintenance technicians and serious DIYers who need a reliable Viton seal for fuel systems, hydraulic connections or high-temperature sealing points. Its broad chemical resistance and high temperature rating make it especially useful in applications exposed to fuels, oils and solvents where standard nitrile O-rings would fail.\u003c\/p\u003e\n\u003cp\u003eThose working exclusively with low-temperature, food-grade, or very soft-sealing requirements may want to look at alternate elastomers or softer durometers; the 90A hardness here is relatively firm and better suited to pressurized or high-temperature settings rather than delicate low-load static seals.\u003c\/p\u003e\n\u003ch2\u003ePros \u0026amp; Cons\u003c\/h2\u003e\n\u003cp\u003e\u003cstrong\u003ePros\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eExcellent chemical and temperature resistance from Viton FKM means fewer replacements in harsh environments.\u003c\/li\u003e\n\u003cli\u003ePack of 25 offers good value for workshops and routine maintenance tasks.\u003c\/li\u003e\n\u003cli\u003eActual and metric dimensions provided make sizing straightforward and reduce installation errors.\u003c\/li\u003e\n\u003cli\u003e90A durometer keeps shape under pressure, improving seal reliability in many dynamic systems.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eCons\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eRelatively firm 90A hardness may be too stiff for delicate or very low-compression sealing needs.\u003c\/li\u003e\n\u003cli\u003eViton is more expensive than common elastomers, so cost-conscious users for simple non-chemical applications might prefer a cheaper material.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2\u003eSpecifications\u003c\/h2\u003e\n\u003ctable\u003e\n\u003ctr\u003e\n\u003ctd\u003eMaterial\u003c\/td\u003e\n\u003ctd\u003eViton (FKM)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDurometer\u003c\/td\u003e\n\u003ctd\u003e90A\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNominal dimensions\u003c\/td\u003e\n\u003ctd\u003e3-3\/4 in ID, 4-1\/8 in OD, 3\/16 in CS\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eActual dimensions\u003c\/td\u003e\n\u003ctd\u003e3.725 in ID, 4.145 in OD, 0.210 in CS\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMetric dimensions\u003c\/td\u003e\n\u003ctd\u003e94.62 mm ID, 105.28 mm OD, 5.33 mm CS\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTemperature range\u003c\/td\u003e\n\u003ctd\u003e-26C to 232C (-15F to 450F)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePack quantity\u003c\/td\u003e\n\u003ctd\u003e25 o-rings\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\n\u003ch2\u003eOur Verdict\u003c\/h2\u003e\n\u003cp\u003eThe Mr O-Ring 343 Viton 90A in a pack of 25 is a solid choice for professionals and serious DIYers who need a high-temperature, fuel-resistant seal that matches AS568 sizing. It represents good value where chemical compatibility and durability matter, though users needing softer seals should consider different durometers.\u003c\/p\u003e\n\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\n\u003cp\u003e\u003cstrong\u003eIs this o-ring compatible with fuel and oil?\u003c\/strong\u003e\u003cbr\u003eYes. The Viton FKM compound is rated for petroleum products, diesel and many fuel blends, making it suitable for fuel and oil sealing applications.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat temperature range can it handle?\u003c\/strong\u003e\u003cbr\u003eThe o-ring is rated from -26C to 232C (-15F to 450F), suitable for most high-temperature air and heated fluid uses.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eAre the sizes exact for replacements?\u003c\/strong\u003e\u003cbr\u003eActual dimensions are listed (3.725 in ID, 4.145 in OD, 0.210 in CS) so you can confirm fit for AS568-based applications.\u003c\/p\u003e","brand":"Mr O-Ring","offers":[{"title":"Default Title","offer_id":48240687055067,"sku":"B07R543HQR","price":114.39,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0724\/1043\/1707\/files\/51Kuv29LevL._SL1000_6cc4427d-86a7-46ae-b572-d35b0359a32f.jpg?v=1771004143","url":"https:\/\/gearmusthave.com\/products\/mr-o-ring-343-viton-o-ring-90a-durometer-pack-of-25","provider":"GearMustHave","version":"1.0","type":"link"}