Brand New in Box! 4 Silicone nano tips designed for a more intensive weekly RegenPen treatment. Cartridges should be replaced after each use. This alternative is a more budget friendly option at a price of $39 instead of $99. This is helpful for people who have long, busy days and can't commit to daily use of the RegenPen. With the weekly cartridge you're getting a .18 mm silicone tip. This means your products are absorbing into your skin deeper compared to the Sensitive (.04 mm) and Daily (.08 mm) cartridges When applying be very gentle on your skin especially if you have sensitive skin. If you have sensitive and delicate skin we recommend the Sensitive cartridge pack. Use the Repair Serum or HA3 for optimal results.