The US-Tube has been on the market for many years, very popular in Scandinavia. You can use it as a body, or as a weight under the dubbing, flatbraid ect. The FF Classic US-Tube fits perfectly on Plastic Tube 1.8mm. We have it in 3 sizes:
10mm/ 0,30gram
15mm/ 0,40gram
20mm/ 0,50gram.