Use this special Protec Back Pack Strap to convert your standard Protec Pro-Pac case (with attachment loops) so that it can be carried backpack style. For Protec cases only. NOTE: Can only be used on later model cases with hoops stitched into the sides of the case near the handle end. This style of case was introduced in 2004. Click here for photo of one of these hoops. If you lost yours, you can download a set of installation instructions in Acrobat format.