Hi peeps, please excuse my ignorance about guitar hardware but I have a small issue

I have an Aria pro II XR series that I just picked up again after not using it for years...It's lost its locking nuts and I've had to find some replacements for it. The small nut I'm holding in the pic (link below) is basically what I used which was really bad for the strings and never actually worked...so now I'm on the hunt to replace the whole locking system...I'm not entirely sure about the size of the nuts as I just rummaged through my tool box and hoped they would fit!

I've had a look online including ebay but they all only sell ones for floyd rose bridges. No sure whether they would fit...what do you lot think?

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