| LMT MRP Complete Upper Receiver w/ 18 Inch Stainless Steel 1:10 Twist 6.8 SPC Barrel - M-6-8S0-CX-SH-X-XXX SPEC II Barrel Lewis Machine and Tool MRP™ and CQB MRP™ Complete Upper Receiver Assemblies Include: Does NOT include bolt carrier Group MRP = Monolithic Rail Platform CQB = Close Quarter Combat |