In the wake of the September 11, 2001, airline hijackings the FIREARMS AND TOOLMARKS UNIT of the FBI LABORATORY has started a collection of small and easily concealed knives. This is the first installment of a continuing effort to collect and distribute information on knives that otherwise may be dismissed as non threatening items. Many of the knives in this collection were commercially purchased and typically can be bought for less than $20. Some of these knives are common items found in most homes and offices. You will notice also that some are made of a plastic material, making them less likely to be considered a weapon. Each of these tools was designed to cut and is fully functional in that respect. Whether used to cut paper, cardboard, or other material, these knives should be treated as potentially dangerous weapons. Each knife is shown with an accompanying scale for size reference and many include an X-ray photograph to show how these weapons might appear if placed in luggage and passed through a scanning device.