I had the same problem searching for a pen that would fit. End up giving in and purchasing the LV agenda ballpoint pen in palladium pm size. The pen cost $120 usd and is available in gold and palladium. They carry the refills for this pen also, they cost $5 usd. This pen is actually short enough to be use for the mini ring agenda as well. I use mine in the small ring agenda. Price is much more reasonable then some of their other pens. By the way, they also have this same size in the pencil with refills available. The product # for the palladium pm ball point pen is N75005. Also, they are available in two ink colors; black or blue.