Hi Cam, the guys in Holland have mainly bought the Ritmo L's for MP75 projects and this is where they get this number from. As You will know by dealing with Les, it really depends on material quality, application, conditions and of course the knowledge of the user. PFT state 20 m but I know of people in the UK and other countries who do a lot more. But as always the more metres you use the more wear and tear on the R&S.