Not a 490, but my echo cs-450 has a felling sight formed into the plastic, which I used once...and the tree did not go where I intended... I took a closer look after and the felling line is not 90 degrees to the bar! The felling line is also not filled in as a black line, its the same orange color as everything else. Anyway, after examining it, the HANDLE is infact 90 degrees to the bar and makes a good felling sight. Its like they put the felling line molded into it, because it looks cool/should be there yet it has no function. In their defense they did not mention felling sights on the saw in the manual....
So now that you are like ok thats nice we are talking about the 490....what I'm saying is, is even if it HAS felling sights, make sure they are actually 90 degrees to the bar!!!