inside mate, great thing is ya just glue it to suit ya motor. (front or rear shaft.) I used a 28mm but i reckon a 40mm would be better to fill out the cavity a bit, i had to pack the sides on the 28 to get it firm in there. a bit but no dramea on the pylon which is a 2600kv

By the way jaav watch this space for my ultra stick spad coming soon.