Here we have a Vintage, Simplex Prestige Rear Derailleur for SPARES & REPAIRS.
The mech is a friction-only derailleur and is in overall excellent condition apart from the rear spring (which I’m pointing to in one of the pictures) which is damaged as it doesn’t create tension as it should.
The adjustment bolts turn fine and there is no rust.
Prior to sale it’s been cleaned and degreased and is now ready to be repaired by someone who knows these mechs.
It would make a great addition to a vintage bike build project.