1/3/5/7/9/12/36/42/pin Nano Square /Nano Round For choose Protective cap Each cartridge is sterilized and individually packed For Dr. Pen Derma Pen. Each needle can be used for 4-6 times according to treatment. Needle Main Function: 1 pin: tattoo, eyeliner and eyebrow. 3 pin,5 pin, 7 pin : tattoo and eyebrow. 9 pin: repair Mole pit; remove acne; eliminate stretch marks, wrinkles 12 pin: repair acne pox pit; remove acne; eliminate stretch marks, wrinkles 36 needle: whitening; watering; spot removing; skin rejuvenation; shrink pores. Nano needle: painless nutrition importing, whitening skin; spot removing; skin rejuvenation. Nano silicone: painless operation, import nutrients, pit repair, lightening skin color, restore skin activity. About Dr. Pen: The AMTS (Auto Microneedle Therapy System) helps to: Repair and revitalize complexion. Reduce sagging skin, age spots, scarring (including acne scars), unattractive large pores & sun damage. Reduce deep-set and fine line wrinkles. Restore skin's natural, youthful beauty. Reduce cellulite & stretch marks. Reverse age-related hair loss, restoring healthy, thick hair, a hallmark of youth. Results rival those of aestheticians and cosmetic surgeons. This listing for A6 Dr.Pen replacement cartridges only.