Lage Manufacturing Left Folding Stock w/ Picatinny (1913) Rail Adapter: works great, no issues. 

Designed for use with receivers that have a Picatinny M1913 rail mounting point. This includes the BRN-180 Lower Receivers, MCX, MPX Copperhead, and many other platforms that utilize a rear picatinny mount.

Stock adapter and folding stock mechanism manufactured from 6061 aluminum and finished in flat black anodize. Buttstock is manufactured from glass reinforced nylon, this stock is not only strong, it is more comfortable to shoot in extreme cold or heat than an aluminum stock

Easily un-folds and solidly locks in place. This buttstock features a sling mount on the top rear of the buttstock. Stock can be configured to fold to the right side by reversing the folding mechanism..