The Boker Rocket Pen is designed by custom knife maker Darriel Caston and it's not your typical ballpoint pen. The oval design means flatter sides that feel elegant and comfortable in the hand. It features a very satisfying bayonet mechanism with a lateral slider. You can get it in anodized black aluminum or brass. Using this pen is addictive and it is also incredibly durable and attractive. Everything about this pen makes it a joy to hold and use. It takes Fisher Space Pen Refill #PR4 and Parker-style refills.