Ideal for those pursuing finicky trout, the Rio Mainstream Sink Tip Fly Line helps optimize rod performance with its slightly heavier, shorter head length. Rio&';s 12&'; weighted tip is precisely tuned to sink at a rate of 3 per second. With a supple, memory-free core with slick coating this fly line excels in coldwater. Slightly heavier than standard fly lines "loads easily Weighted tip tuned to sink at a rate of 3 per second Supple, memory-free core with slick coating excels in coldwater.