Staedtler 158 SB6 - ergosoft jumbo crayon, 4 mm, 6 pieces in box tiltable (Office supplies & stationery)
My son (7) writes and very much like painting with these pins. They fit comfortably in the small child's hand. And when the pin falls down sometimes, does not break the mines, as it has a "protective shell". Price-performance absolutely great.
