- Flexible-Tungsten is nothing less than one of the most Innovative products we have seen in years. These are normally made for Nymph fishing, but we also use it as weigths on our Tubeflies. Because its Flexible you can 'Click' it on the Tube, from 1,8mm up to 3mm tubes is no problem. Its very very strong, super flexible. We have it in 3 sizes. 2mm/9mm 0,30 gram - 2,5mm/10mm 0,40 gram 3mm/11mm 0,50 gram.