The Zak Tool ID Card Holder is very useful as an ID holder if it is placed in the shirt pocket and the pocket is buttoned/snapped closed over the top of it. The card holder may slide up and off if not secured under the pocket flap (as shown in the current picture). Also, placing it under the pocket flap keeps the slot in most uniforms where pens are intended to go free for pens and pen-style handcuff keys.The handcuff key is permanently secured by a rivet and a plastic washer helps the key stay firmly in the position it is rotated to.The whole thing is 3-1/2 inches from top to bottom when the key is folded back and is 1/2 an inch wide. It is very springy and tight for holding IDs and paperwork in place. The matte black finish is non-reflective and does not stand out or look awkward on a standard black uniform.It is always advisable to keep at least one backup handcuff key on your person when using handcuffs. If you need an ID holder and a better place to keep a backup key this might be just the thing.