These Pilot FriXion Ball Erasable Gel Pens allow you to erase and rewrite repeatedly without damaging documents. The thermo-sensitive gel ink formula disappears with the erasing friction of a rubber tail plug eraser on the pen. Erasing leaves no residue or debris. Each pen can write on the same spot that has been erased. Each gel rollerball pen delivers smooth writing gel ink and is not recommended for signatures, examination papers or official documents where writing needs to remain permanent or exposure to extreme temperatures. There is no-clip, and the pen leaves a fine .7 mm line.Embroiderers and quilters love this pen for tracing their patterns or outlines, as the ink is heat and cold sensitive. When the traced designs are heated with an iron they disappear and if placed in the freezer, the lines reappear.