In every venue where lead core is not allowed you need a material that will do the same job, so a sinking anti tangle and abrasion resistant material. The XTR Anti-Tangle Sinking Tube can do all this and it is, of course, environmental friendly. It is sinking due to the high specific gravity given by the tungsten powder added to the silicon sheath. The anti-tangle surface make it simply perfect for ultra-clear waters, particularly the Camo Green color is the right solution when you have herbs while the Camo Brown is much better on very dark bottoms. The inner diameter of the tube is 1 mm and so it is very easy to use.