Response to Hi, John, This Impeller Screw Fastener Size is 1/4" and the Thread Pitch is 20. It does keep the impeller secured to the motor shaft. 

An image is worth 1,000 words! Add an image or two to your comment to help ensure it is understood accurately.

Yes, please email me exclusive discounts, swimming pool tips and helpful how to guides. This comment may be posted on a public site. Do not include: HTML, references to other retailers, pricing, personal information, or any profane, inflammatory language.