https://www.amazon.com/Shengshou-7x7x7-Cube-Puzzl-black/dp/B...
Apparently the 7-cube bulges slightly which helps to hide that the larger sized edges / corners
https://en.m.wikipedia.org/wiki/V-Cube_7
https://www.amazon.com/Shengshou-7x7x7-Cube-Puzzl-black/dp/B...