FWIW, I bought one of the Pica Dry pencils a couple of months ago and have used it daily since.
At first the whole setup appears and seems a little 'odd', but I can tell you once you start 'using' the pencil, you will wonder how you ever got along without it.
The more I use it, the more I grow to appreciate it. Every aspect of how you use the pencil just works and works very well.
The sheath and the way the pencil has a slight friction fit means your pencil is exactly where you need it, exactly where it should be- never slips, never slides away, never falls out, never marks your clothes.
The pencil fits proud in the sheath, so even with large heavy wet gloves, you can easily access your pencil- never fumbled- not once. Brilliant.
Sharpener is in the tip of the sheath, too easy.
I do bathroom renovations. Ever tried to mark waxy porcelain tiles? I don't know what's in this pencil lead... But for me there are two requirements that are critical....
I must be able to actually mark the material (and read the mark) and equally I have to be able to remove those marks from the finished product.
Without any doubt this is the most extraordinary function of this pencil...
It is a struggle to mark waxy porcelain, but this pencil will do it- that's a bit like marking wet glass- outstanding. Marking unglazed tiles is usually dead easy, BUT getting those marks off the finished product can be a nightmare.... So far, every material I have used, I have been able to remove marks, fairly easily. Sometimes needing a damp rag- but that's perfectly acceptable in my book. Now, I must say, I haven't yet used this pencil on sandstone- which is possibly the most difficult material to remove pencil marks from, so that's still an unknown. (A few years ago now I was called in to quote a job that had gone legal because the owner had $40k worth of Helidon Sandstone laid and you could still see every single pencil mark the tiler had made on every single piece of stone- I declined to quote but I do know the whole job was ripped up and replaced because of those pencil marks being indelible)
Anyway, I have to say that overall I'm bloody impressed, and that's saying something.
Over the years I have bought every pencil gadget that has come into my local tool shop and so far I have never used one more than a day.
This Pica Dry Pencil is truly a remarkable tool. Try it, you'll like it and it may be the last pencil you ever buy.