Bought this years ago and it has sat in its box in my projects stash ever since.  This is a high quality replica of a stock Colt created for a PDW Prototype around the year 2000 iirc.  It is a very solid piece and our very unlikely to bump into another at the field.  It bolts directly onto the stub on an M4 AEG inplace of the stock pipe.  Fixing bolt and washer is included in the box.  Obviously this will require a forward wired gun as there is no battery space in the rear.

Price for this unique piece is £25 plus fees and p & p.