Look on page 13 of the manual,where it says "preflight checking list" it shows the mark there.Like I said before, mine came out just a fuzz nose heavy,but it sure flew great! I bet wind would be a different story though.... Good Luck,go lipoly if you can,I got mine off of ebay,$30.00 for the pair,shipped,3.4 ounces for 1900mah!