I have recently made purchase of 2 heavy duty pens with a mind toward protective use for locations restrictive of other means ie airline or international travel. The two that I chose were both aluminum body. One is equipped with a rite in the rain cartridge, is spiral fluted for grip, and has a stainless steel glass breaker tip, and an aluminum pocket clip(removable/replaceable), priced approximately 100$. The other is equipped with a pressurized "space" cartridge, horizontal ridges and a knurled center section for grip, steel pocket clip(removable replaceable), priced approximately 25$. For others who have done the same thing, what were the considerations you had in mind when choosing your pen in regards to price, materials, design/features, etc.?