If you are tying larger flies, or especially those that have longer shanks like streamers and saltwater flies, the CerMag offers you the additional length you need. And often times, these flies require heavier, tougher thread--which is why we have built this bobbin with a high-quality ceramic tube, to help you avoid cutting thread due to extreme wear and tear. The durability and length of the CerMag will keep you cranking out those hefty patterns all year long. FEATURES: Stainless steel with zirconia ceramic insert Surgical quality stainless steel. Very high pressure click drag system Heavy duty thread tension, 2-16 ounces thread tension Perfect for longer hooks such as streamers Excellent for spinning deer hair