1. Material

• Roller drum: Medical-grade stainless steel or titanium
• Handle: Plastic or alloy for ergonomic grip

2. Needle Specifications

• Needle length: Common sizes:
  
• 0.25 mm → boosts serum absorption
• 0.5 mm → improves skin texture, fine lines
• 1.0 mm → for scars, wrinkles
• 1.5 mm+ → for deeper scars, hair regrowth (professional use)
• 
  
• Needle diameter: Usually 0.20–0.25 mm
• Number of needles: ~180 to 1200 depending on the model

3. Size & Weight

• Length: ~13–15 cm
• Weight: ~50–100 g

4. Usage

• Frequency depends on needle length (e.g., 0.25 mm can be used daily, 1.0 mm every 4–6 weeks)
• Must be sanitized before and after use

5. Extra Features (in some models)

• Replaceable heads
• Adjustable needle length
• LED light therapy attachment