This particular pen will write consistently and clearly in adverse weather conditions e.g. minus temperatures as low as -20c and on wet paper smoothly without blurring. This makes it the ideal pen for those who work outside. Additional features include; fade resistant, water resistant, UV resistant, chemical resistant, tamper proof and a comfortable grip. These pens come in sets of 5, so please order per number of sets, e.g 2 sets equal 10 pens.