HiDon't know if this will be of use to anyone but I struggled to find a suitable two foot screwdriver for my Sumatra valve .Anyway while in my local "Do it yourself" store I saw some mild steel rod. Now this was approx 4mm x 14mm x 2m and just happenedto fit the slot in my valve end exactly. All I then had to do was measure 24" bend a right angle and cut off the excess. I then covered it with plastic shrink wrap to stop it scratching the threads in the tube. This works really well the only thing you have to watch is because of the leverage in the dog leg it would be easy to tighten the "o" ring up too much.