At the side of your spool you will see a little round silver "button" (on shimano reels) where you can put your line throuhg. Now before you do that, you walk out say a 100m of line off the spool, before reeling it back in, twist your line around the silver "button" and reel all the line back in. So as you cast, the line will come off the spool up until 100m's, and then it wont go any further as it hits the clip. So the line cannot go more than 100m's off the spool. Therefor you are casting every cast at 100m, creating an accurate feeding spot.