This is a custom shaped motor mount to fit the Droidworx Skyjib 8's boom-block.
The motor mounting holes are
- 4 x 4.2mm spaced apart in 30mm diameter (fit our custom 4226-350 motor)
- 2 x 3.2mm spaced apart in 19mm diameter, and
- 2 x 3.2mm spaced apart in 25mm diameter (to fit Tiger 3515-400 motor)
As you can see they are designed with fins (40 of them) each 2mm thick for strength and are meant for dissipating heat from the motor (if you chose at least the Alumide).
This mount is 7mm thick at the thickest portion to clear the collar at the end of the motor shaft.
The holes to match the SJ8 boom block are spaced 43mm apart in M4 size.