Thanks, guys, I will have a look. Yes, I has lost one on the balcony in the middle of the night. I was afraid it had fallen off the balcony and didn't want to go down with a torch at night (somebody could have called the police because they might have thought I was a burglar!
), but luckily I then found it on the balcony... Still, it made me think it is handy to have a spare one.