This Hydra Stripped Modular Lower comes with a 9mm H5(MP5 Style) Interchangeable Magazine Well and offers the ability to change Magazine Wells on your Lower Receiver to accommodate whatever caliber you want.  Leaving it as a Stripped Lower allows any AR-15 Mil-Spec Stock and Fire Control Group (FCG) to make it complete. Ideally suited for use with the Hydra® Quick Change Barrel Upper Receiver (QCB-D), where you can change calibers by switching out barrels as well.  This is a Stripped Modular Lower Receiver and only includes a 9mm H5 (MP5 Style) Interchangeable Magazine Well.