Why not try Tyvek wristbands? Use a biro or marker pen to record the split times you are looking for. They cost pennies. Once in place they are waterproof and incredibly tough.
Some events already give you the wristbands (to allocate start times/ start blocks). In which case take a pen from a betting shop with you and a list of your split times to write on the wristband.
I've included a link to my husband's website to show how to put a wristband on
Lucozade always give them out for the London Marathon.
If you print your own - just cover it in sellotape to make it tough and waterproof.
Sorted.
Mmm, tasty Spam, served 6 years after it might have been useful
they were giving away pace bands at the Expo in London but the trouble is you had to get there quick as anything over 4.30hrs went very quickly!!!
yes i've heard of people writing the times up their arms 2old!!