This is a bolt on fixed UMP style stock and pistol grip for the USC rifle. It"s a great solution for this that can't have a folding stock or high cap mag and dont want to go through the expense of a Full UMP conversion. This set up bolts up with no modifications needed. This set up comes with dual sling pin for mounting that replaces the need for tools to disassemble for cleaning and gives you a solid rear mounting point on either side for a sling.