Special needles for hand sewing sail and canvas repair work. These needles have a triangular shank which opens a hole in the fabric that does not tend to fray the twine.
Needle size increases as the number decreases. The #16 needle is good for most work, but you will want to use larger needles for sewing through many layers of fabric and smaller needles for seam work.
These needles have triangular points and long eyes for easy threading. Canvas workers and sailmakers prefer to use a triangular shank needle to open a rather large hole in the fabric. That cuts down on chafe problems when pulling a long length of twine through the sail again and again.