Hello! I've got a slendertone system - one for the stomach and one for the arms. Pity they don't make one like a wetsuit, for absolutely everywhere!!! My daughter, who is 18 and slim, is also using the stomach one, and it has definitely made her tum firm, whereas before it was a bit soft. So I'm assuming the same thing is happening with my muscles, only they're currently hiding under another 3 stone of flab, so it'll be a while before I find out!
While I can use the stomach one at about 60, I can't get above 18 for the arms - it feels so sensitive there! But last night my arm was literally jumping with each contraction (while I was trying to post here - lol!) so something is definitely happening. But whether this will result in less flappy bingo wings....it'll take a few months to find out.