The line flows free between two wheels. When you pull the trigger, you pinch one wheel against the other. Then, when you crank, you turn one wheel and it feeds the line back into the bottle. Very simple, so very little to go wrong. I bowfish an average of three days a week in the summer, and the only problem I've had is the screw come off that holds the crank handle on. I love them, but some who shoot tournies prefer a spincast for faster retrieves and followup shots.