The Hinderer Investigator Pen continues the history of innovation in hard use writing tools from Hinderer Knives. The Investigator Pen packs a ton of punch in a small package. Designed and manufactured to the same high standards as the Extreme Duty Pen, just in a smaller size. It uses a full size Fisher Space Pen refill so it can handle a ton of writing. A discreet, take anywhere tool that can stand up to hard use. Specifications Material: Stainless Steel Length: 4.375 in Weight: .8 oz Accepts commonly available Fisher Space Pen refills (PR4B)