PANZER AR57 ULT UPPER ASSEMBLY 5.7X28MM 16" - ULT 0116 DETAILS: Brand: Panzer Arms Model: AR57 ULT Product Type: Upper Receiver Caliber: 5.7x28mm AR57 16" Full ULT M-LOK Upper, AR57 Mfg, Factory brand-new. Comes with a 16" light-weight barrel with M-LOK rails. This AR57 Upper Receiver Assembly transforms any AR-15 reduced to a rifle wit