Renzetti Ruby Tip Bobbin- Midge- Renzetti bobbins are in a class by themselves. The ruby tip provides for ultra smooth thread delivery and excellent wear resistance. Plus, the smooth spool knobs are perfect for fine detail and lighter denier threads. The standard length tube is 2-inches long and is 3/32-inch in diameter. Also available in an extended length version (saltwater) upon request; the tube is 2 3/4-inches long and 1/8-inch in diameter.