So according to this url - https://www.thesprucecrafts.com/the-scoop-on-action-figure-size-scales-17899 - 1:18 scale action figures are 3.75 to 4 inches tall. I'm trying to build custom figures between 4 to 4.25 inches tall. I am looking to purchase ball joints for decent articulation but I'm having a hard time determining the size of the of the ones Ive6 found online. I've been looking on ebay & amazon and found hobby base brand joints but can't determine what scale they're for.

Can some one please confirm that 1:18 scale is the appropriate size for 4 to 4.25 inch figures and does anyone know of where I can get joints for 4 to 4.25 inch figures?