I found mine as FOD down the back of an OCU Buccaneer bang seat, not a UK one but a Skilcraft US one. Anyhow, 40 years later I still use it. It is on my kneepad that I use in the mighty PA28-181. I also use it to write routes on the inside of the winscreen when i am on a long journey. So if you get into a hire car with greasy marks on the top corner it may have ben mine. The GPS does a good job but does not see the big picture and hence the Chinagraph notes. I have a box of leads (blue) now 50% depleated so should just last me out.