1. Only Support for 3Doodler Start Pen: This 3D Doodler pen refills pack is only for 3Doodler Start 3D printing pen. The PCL filament refill diameter is around 2.5 mm, so it's NOT FIT any other brand 3D pen. It's ONLY FIT 3Doodler Start 3D Pen! 2. 25 Colors 250 Strands 2.5mm PCL Filament Refill Packs: The 3D Doodler Filament Refills packs include 25 vibrant colors (17 common colors, 4 glow colors, 4 light colors). The glow filament refills can glow in the dark after absorbing light. Each color 10pcs total 250 pcs, Enough to create use. 3. and Safe Raw Materials: The 3d doodler pen refills raw materials is PCL, and the PCL material has a low printing temperature, is safer, nontoxic, and allows for smooth printing; Each strand of the 3d doodler pen refills is quality controled before being packed. 4. Resealable Packaging Design: This 2.5mm PCL filament refills packs for 3Doodler Start 3D pen are designed with resealable openings; This design enables you to reseal the package after use to keep the remaining filament refills dry; It also allows for better storage. Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.