well i´m not sure i understand correctly but i have been looking at the drawings & i think that 25x2mm is what you need & not 25x3mm , the iner diameter of the 25x2 is 21mm so to fitt a plate into the tube it would have to be papper thin but the tabs on the plate in the drawing are 5mm thick & therefor must be a little smaller to fitt. i wish i could make a drawing it wuold make it alot easyer to explane

but hope this makes sence.
samy