Well, just the Jetpack/Thruster model from GTA V.

Yes, there's already a Jetpack/Thruster model included in a vehicle pack, and this one is not coloarble either, but this one got more details and moveable parts.

You can find the original SFM addon here:
https://steamcommunity.com/sharedfiles/filedetails/?id=1229698731

Includes:
mark2580\gtav\jetpack.mdl

Credits:
Rockstar Games/Rockstar North - Grand Theft Auto V
MARK2580 - Porting to Source Filmmaker.
NeoLin - Porting to Garry's Mod.