Just got a new ball head and wanted some extra QR plates for some of my lenses etc. This size is perfect. I previously bought 60mm and they were too big. The descriptions recommend 40mm for smaller cameras, but 40mm is perfect for my tripods/monopods that I own. And compared to previous tripods, 40mm seems like the standard size. Order 40 and 60 when in doubt, but again 40mm seems more standard. It appears to be very durable and is excellent value for money. i want to buy more I couldn't be happier. I highly recommend. Update 11/15/18 After trying this on my Vanguard tripods (Altra Pro 2+ and Veo 2 CB) I was disappointed that they didn't fit. It didn't occur to me until a month later that I should try to remove those metal screws on the underside of the plate as it didn't allow me to sit flush on those brackets. Well I removed them and now they are pristine. Now they really serve their purpose and everything I can offer them. I have multiple camera bodies and plan to install one for each camera. Once again what a great high quality product.
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