This is a Pentair  801428 mechanical seal. They are a direct aftermarket replacement for the OEM version and suits all Onga-Pentair standard pumps as listed below.
This seal fits the following pump sizes.
Looking for a repair kit for these pumps with seals, O-rings & Bearings. Click the corresponding links below. 

Pump Model Silentflo-550100

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Pump Model Silentflo-750103 

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Pump Model Silentflo-1100100

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Pump Model Silenflo-1500100

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This seal fits the following pump sizes.
Looking for a repair kit for these pumps with seals, O-rings & Bearings. Click the corresponding links below. 

Pump Model Max-E-Pro730100

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Pump Model Max-E-Pro930100

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Pump Model Max-E-Pro1100100

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Pump Model Max-E-Pro1500100

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This seal fits the following pump sizes.
Looking for a repair kit for these pumps with seals, O-rings & Bearings. Click the corresponding links below. 

Pump Model EnviroMax 1500

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Pump Model EnviroMax 800

Visit My eBay Store for pump repair kit