Abstract: An attachment device for attaching an implement, such as a knife, pager, telephone or the like onto a belt or other garment. The device includes a clip assembly for attachment to the belt, and includes a slot having an end portion circular in shape with a radius larger than the width of the slot. A pin fits into the slot only when at least one flat surface on the neck portion of the pin is parallel to one edge of the slot. The pin is allowed to rotate via the circular shape and the pin having a stem diameter corresponding the circular shape. This provides a locking mechanism where the narrower width of the slot prevents the pin from exiting the slot unless the instrument is turned a specific angle.