Fly reels are normally manual, single-action designs. A rotating a handle on the side of the reel rotates the spool which retrieves the line, usually at a 1:1 ratio (i.e., one complete revolution of the handle equals one revolution of the spool).
The centrepin reel is also used for coarse fishing, where one can use it to trot on a fast flowing river. Normally, the float would be pulled under because of the fast current, but the centrepin reel automatically releases line, thus making the float not go under.

DIA 0.2mm-3mm
on spool(20M.50M.100M.200M.500M.1000M)