Recording set times - 'wet' tools?

Hi Does anybody have any products that they use or could suggest for recording set times during a set. In other words, some sort of small whiteboard / clipboard that can be used with some form of pencil/pen that can be used in the wet and then rubbed off later? Thanks Rob An idea I came up with from counting cards: Say you are doing 10 x 100's on 1:30 with a goal time of 1:10 per 100. If you go 1:11, that is a +1, if you go 1:08 that is a -2. Keep track of your count. If your count ends up at "0" then you averaged exactly 1:10. If your could ends up as +5 then you averaged 1:10.5. It takes a little brain power but it also causes you to be more goal oriented with your set and more mindful of that goal during the set.

Hi Does anybody have any products that they use or could suggest for recording set times during a set. In other words, some sort of small whiteboard / clipboard that can be used with some form of pencil/pen that can be used in the wet and then rubbed off later? Thanks Rob An idea I came up with from counting cards: Say you are doing 10 x 100's on 1:30 with a goal time of 1:10 per 100. If you go 1:11, that is a +1, if you go 1:08 that is a -2. Keep track of your count. If your count ends up at "0" then you averaged exactly 1:10. If your could ends up as +5 then you averaged 1:10.5. It takes a little brain power but it also causes you to be more goal oriented with your set and more mindful of that goal during the set.