Richard, The suggestion was based on the information that was provided in the OP. If you are considering sending the entire or parts of the Lenz system back to Lenz, it is sensible to have a compatible back-up system hence the suggestion to use the MultiMaus either as a complete entity or just the handheld unit. The added complication of the touch phone was not mentioned and is not really part of my answer. Buy a complete MultiMaus system, it is just as cheap in the long term, currently my 'spare' MultiMaus is running under my Expo layout and I also share the MultiMaus handheld with the Lenz system that powers the large layout, whilst the Lenz handheld units were abandoned some years ago.