These needles are used to ventilate hair through lace. The lower the number, the less hair the hook of the needle will grab. The higher the number needle, the more hair the needle will hook when ventilating. Generally, the amount of hair each needle will grab is the same count as the number of the needle. Ex. The #3 needle generally grabs 3 strands of hair at a time. The #8 needle generally grabs 8 strands of hair at a time.

These needles come in 8 sizes:
1, 2, 3, 4, 5, 7, 8, 9