Thanks, folks. As it happens I can't find the blasted thing anyway. Can't remember if I gave it away or what. So I won't be mincing vegetables!
The idea only came up because MrB bought a supposedly high quality mandoline for slicing and chopping veg but I've found it almost useless, possibly because it seems to have been made with a big male chef's hands in mind. I find it just too big and awkward and it doesn't seem to do what it's supposed to do.
MrB made the same mistake with some handmade, Sheffield steel tailors' shears. I simply can't control them with one hand. Practically my whole hand goes through the lower handle loop! I wasn't going to say anything about that to him because it was a kind thought of him to get them but since the mandoline causes the same too small, arthritic hands problem I thought I better tell him so he doesn't waste any more money on things I can't use ?