The SB5 was developed for use on MP5, MP5K Reverse Stretch, and HK53 clones (buffered carriers only). It comes with an adjustable stabilzing nylong strap.
The ATF has determined the pistol stabilizing brace was neither designed nor approved to be used as a shoulder stock, and therefore use as a shoulder stock constitutes a redesign of the device which alters its classification and subjects it to NFA (SBR) laws, meaning you need to register it and buy a $200 tax stamp to own it. Do Not install and use this brace as a shoulder stock.
Features and Specifications:
HK MP5, MP5K Reverse Stretch and HK53 Clones
Will Not Fit HK91 or MP5K Clones SB5-01