Been thinking about this a few days . Why I don't like the wing 2017 3008 Piston Filler .. First when you put the cap on the back of the pen = Twisting the cap - moves the piston ( I have 2 of these pens - both are the same ) Second there is no piston lock ... ( I have two pens with piston locks ) The price for a pen with a piston lock , is more or less the same as for the Wing 2017 3008 .. So why would you not buy the pen with the piston lock ? + The cap activating the piston - Thats a deal breaker ... I watched a few reviews and they did not mention this .. Anyhow , made a video ...