As the title says, its an APM/PX4/Pixhawk pitot tube cover. I designed this for two reasons; 1) Easy calibration 2) Protection during transport. It covers 55mm of pitot tube, which seems to be enough for most pitot tubes protruding from a wing or nose. This probably wont work well when externally mounted with a bracket, as it is designed for the first 1cm or so to be encased in an airframe, glue, etc. I almost made a flange for it so it would butt up perfect against my airframe, but then realized it will only work on my airframe (which is not on the market... yet) so I designed it for everyone. As a warning, if your printer is not tuned well and cannot make a perfect circle, this may fit a bit tighter than it should. With an accurate printer it will fit snug, but not too snug or it will be air tight and wont allow you to calibrate. If it fits a bit loose, I fixed it with a single layer of Scott magic tape (no more than exactly ONE layer!) This should be placed at the base, not the tip, and the pitot tube will slide on and be secured with a bit of friction. perfect for transport.Just print at as fine resolution as you are willing (.1mm-.3mm). It should slide right over the pitot tube. If it is a tad loose, use a single layer of scotch (clear) tape at the base (NOT THE TIP!). This will help secure it during aircraft transportation. I have found that this is not air tight, enough to disrupt pitot/static calibration, however with the tape in place it often can become air tight, or close enough to mess with calibration. This being said, if you use the tape method to secure it for transport, simply slide it past the tape so that it is no longer air tight (snug is fine), then calibrate your apm/pixhawk. You might experience a slight change in airspeed and altitude as you slide it off, however once removed completely airspeed and altitude should return to zero. Goodluck!