Do you mean Centrepin? Centrepin and float reel are names for exactly the same reel. The centrepin as Zach mentioned are used for drift fishing with floats. The current takes the float down river and the float pulls the line off the reel in free-spool mode (similar to a bait-caster). You can literally drift as far as your eyes can see the float (although if other anglers are downstream of you, it isn’t very polite to do).
Here in Ontario, they are a tool regularly employed by steelheaders. The vast majority of centrepins only have a basic clicker when you switch from free-spool – like a click and pawl mechanism –