Before you glue a wear plate (this stainless steel plate) to the maststep, check if you already have such a disk under the gelcoat. (Boats over sailumber ~ 100.000 already have it.) To check this, you take an instrument for locating/detecting electrical cables in walls. You take the most sensible level of this detector and check from the waterside of the hull (a the area just there here the maststep is).
The Laser Classrules (Part III, No. 19a) does only allow "a" disk (thickness: lower than 1mm). This is not the disk as described above, if already has been installed such a disk by the Laser builder.
To be on the save side of the Cassrules, you are permitted to use either a carbo disk or a wearite (PTFE) disk. There have been disussions at the fomer ILCA-NA Email-list about the question to use both disks (glued together) but this discussions did not end with a clear result.
I use the PTFE-disk that is loose (not glued) between the mast and the base of the maststep. Also, I use a thin film-collar (UHMW/"Ulta High Molecular Weight"-Film), wrapped around the mast in the mast tube, to prevent wearing between the wall of the mast tube and the mast. This is permitted by the same Classrule as mentioned above, too.