Key Features of Classmate Octane Gel Pen Japanese Water Proof Ink Stylishly Sculpted Design Classmate Octane Gel Pen (Pack of 20, Blue) Price: Rs. 180 Classmate Octane Gel Pen. The perfect pen is a must to sign off a deal or leave a note for a loved or just plain filing minutes at a meeting so gear up with the best that the stationery world has to offer. Rubber Grip for Easy Writing Constructed with a rubber grip, this pen gives your hand the best grip so there is easy flow while writing and no accidents. The grip also makes sure that the pen does not fall out easily or roll off the table. Water Resistant Ink-Smudge FreeThe pen offers smudge proof writing as the ink is water resistant and you can always be sure your information stays safe and does not bleed out.