The Pro Sportfisher Cones are "classic" coneheads, of course, designed to fit perfectly into the Pro tube system - all sizes fit perfectly on any tube with an outer diameter of 2,2mm. The Pro Cone is the right choice when you just want to add a little weight to help the fly penetrate the surface, and balance the weight of the hook. Fitting a cone head to the front of a tube fly covers the final thread wraps, so the fly becomes near indestructible. We&';ve worked hard in the design to give you as much space as possible in the cavity of the cone while still retaining a suitable amount of weight. Pro Cones are often combined with DropWeights, BulletWeights, RAW Weights or FlexiWeights - to add that extra durability and fine-tune the weight of the fly. Pro Cone Specs: X-Small (11 pcs/pk): 4.5mm, 0.10 grams/1.54 grains Small (10 pcs/pk): 5.5mm, 0.18 grams/2.78 grains Medium (9 pcs/pk): 6.5mm, 0.30 grams/4.63 grains Large (9 pcs/pk): 7.5mm, 0.40 grams/6.17 grains ** Pro Sportfisher Pro Cones will fit all: Pro Microtube, Pro Nanotube, Pro Flexitube 40/40 and Pro Classic Medium tubing options**