The red is the pen help to correct your sitting position. The head of this special pen will stop to function once accessed not in the upright position. This is to prevent early myopic eye and hunchback 。 The whole set including special pen; ball- point pen; gel pen; and pencil ; refill ;
Yishun MRT through 93696895 for detail. Or your near MRT station. 4 sets will be much cheaper .