Bulb

 Bulb - is opposite the sharp edge of a sewing needle. It can be round and flat. The first option is most common in industrial sewing machines, at least at the household overlock. Flat bulb is only used in medium-sized versions for home sewing. If you put a sewing machine needle with improper bulb, it will affect the quality of manufactured products and may even lead to serious damage. In order not to make the wrong choice, should carefully examine the flask. As a rule, it is labeled, lets you know what type of machine is suitable given the needle.