Looking for compatible seat post for Trifox X18

[JosephOutdoors]

The seatpost for my Trifox X18 doesn't seem to readily fit any of the saddles I have, both oval and round rails. I'm sanding it down but just in case, are there any compatible seatpost that anyone can recommend? I've only ever used the standard 27.2 round seatpost so I'm not familiar with the names of the aero style posts.

Thanks.