Adaptateur de montage en T Svbony 1,25'' avec filetage M42 - F9103A

This is the fault of poor naming conventions from the past. With cameras the "M42 mount" has a 42mm diameter and 1mm thread pitch, whereas "T-Mount" has a 42mm diameter and 0.75mm thread pitch. The M42 in the title made me think this was the M42 mount with the 1mm thread pitch. I was wrong, and it is in fact a T-Mount.