This is your basic spool of leaded solder with a 63/37 water soluble resin core. 0.031" gauge and 100 grams. This is a good spool for more advanced users that should last 6-12 months depending on how often you solder.
Drill has a large scraps discharge space, little resistance and smoothly during the scraps discharge
Use high quality materials and fine grinding process makes bit more sharp cutting edge, reduce cutting force and broken drill, improve the quality of hole wall
The cutting edges strictly avoid partial hole, ensure the quality
Long life, it can drill 2000-5000pcs under normal working conditions, also can return grinding 4-5 times