‘m working up a sliding pen mechanism for my titanium Swiss army knives like the one in the Victorinox Signature,

http://thumbnail.image.rakuten.co.jp/@0_mall/v-road/cabinet/ikou_20100205/img10492615916.jpg

and I need a tiny slim refill to design it around, something readily available and high quality.

I was thinking of just using the standard plus scale removable pen and cutting the grey plastic tip off and then I ran across the Cross micro pen refill which comes in black, blue and red and costs way less than $5 each. Can anybody tell me the dimensions, length and diameter of this refill?
http://www.ebay.com/itm/12-BLACK-12-RED-CROSS-DRIVER-COMPACT-MICRO-PEN-REFILLS-/300740923915#ht_1449wt_1139

Anybody have a slim short refill in mind that might work better for this? It needs to be less than 1/8″ in diameter and around 3″ long. I know that buying some would be the best bet but I’d like to get pointed in the right direction first. There might be something awesome out there that I don’t know about.