You can find all the replacement parts you need for your Orbea bike at Escapa.
The Orbea Ordu OMX Round Rail Seatpost Nut is an original Orbea replacement part that includes sliding bearings for attachment to the seatpost clamp.
Nut assembly for round-rail saddles on Ordu OMX frames.
Includes slide bearings for attachment to the seatpost tilt assembly.