Art and Stationery Supplies Design Music Pen Cap Design by JiaYi Cai It's a set of pen caps that can produce different sound levels. This product is mainly aimed at the children aged from 7 to 12. As the first choice for children to draw, however, the misplacing and discarding of watercolor pens without cover after using up troubles people. The product optimizes the covers of watercolor pens.It could be served as musical instrument with the combination of tumbler pen caps and gamut. The "music" pen caps can not only exercise the player's patience, stimulate their auditory development, but also develop their perception of music, and maintain their interests in painting.