Dart Guideline

''See exactly where your throw will go with a guideline that adjusts as you change your aim and power. Especially effective when using maximum power.''

 ~ Upgrade description

 is a premium upgrade in Bloons 2 and is available in game. The upgrade is free. It can be accessed by clicking the button that looks like a dart with a separated line in front of it and a red X through it (inbetween the reset button and the music/volume button).

Trivia

 * The actual in game upgrade misspells guideline as "Guidline", but then in the description it is spelt "guideline".