1. Only support for 3Doodler Start 3D Pen: this 3D doodler pen filament fills the package only for 3Doodler Start 3D printing pen; The PCL filament refill diameter is around 2.5 mm, so it is NOT for any other brand 3D pen, it is only for 3Doodler Start 3D pen 2. 22 different colors: these 3D doodler pen refill packages include 22 mixed colors. 15 popular bright soild colors, 4 glowing colors, 3 bright colors F7, glow colors are glowing green, glowing blue, glowing red, glowing yellow; The filament refills can glow in the dark after light has been absorbed 3. Dimensional accuracy: the dimesional of 3D doodler pen refills for 3Doodler start 3d pen is around 2.5mm, and each strand length is 15cm, like the 3Doodler pen filament refills and it works well with 3Doodler start 3D pen 4. Premium and raw materials: the 3D doodler pen fills raw materials from PCL, and the PCL material is low printing temperature, , non toxic and smooth printing; Each strand of the 3D doodler pen refills is quality controlled before packaging 5. Reuse sealed packaging: these 3D doodler pen refills for 3Doodler Start 3D pen are designed with resealable openings; This design allows you to re seal the packaging after use to keep the remaining filament refills dry; It also allows for better storage 6. Scenarios: the package of 3D doodler pen filament refills contains many colors, and it is an excellent gift for your children and friends who have the 3Doodler start pen, a gift on children's day, Christmas or children's birthday