The Hydra Pen H3/H5 Replacement Cartridges are compatible with the Dr. Pen H3/H5 Hydra Pen. These cartridges offer a seamless combination of microneedling and serum infusion, helping to deliver active ingredients deep into the skin for enhanced hydration and rejuvenation. Key Features Pin Options: 12-pin, 24-pin, 36-pin, Nano. Pin Depth: Adjustable from 0 to 1.0mm with the pen. Hygienic & Safe: Each cartridge is individually packaged and sterilized for safe, single-use treatments to avoid cross-contamination. Pin Comparison & Targeted Skin Concerns General Tips for Choosing Pin Types Lower pin (9–18): Better for precision and deeper penetration, good for acne scars and stretch marks. More painful. Higher pin (24–42): Covers more area, good for texture & tone. Less painful. Nano: Great for skin tone & glow, serum absorption, and daily use. Painless. Legal Disclaimer: Please note that Dr. Pen microneedling cartridges are classified as medical prescription-only devices, intended for use by licensed healthcare professionals for the treatment of acne scars. These devices are for use under the supervision of a licensed medical provider. Nano cartridges are available for consumer use and are designed for non-invasive skin exfoliation. The manufacturer and retailer are not responsible for misuse or adverse effects caused by improper use.