Exactly what beeverfishing said !! the spool can be tightened so it wont turn or loosened off so a fish can run . I have the dowel cut about 22" this seems to be a good length for sensitivity , its quite sensitive , I haven't used it with the flag yet so m not sure how that will work .. Ill post when i have used it a few times .
Oh they are cheep to build too , I got material for two at H-Depot for $10 ( minus the reel) flag spring ...old wiper blade steel ..