With the insane California laws that treat law-abiding citizens as criminals, it’s still important to maintain compliance. If you are looking to build an AR-15 from an 80 lower, this combo pack includes a California compliant ready lower receiver with a lower parts kit and magazine lock. What makes this combo a must is the newly designed magazine lock functionality. Once the fire control pocket is milled and you’re ready to install the lower parts kit, you install the magazine lock by simply inserting the plunger and spring into the pre-milled hole and tighten into the magazine catch and magazine release button. Once installed and the upper is attached, the magazine will not drop until you break the action by disassembling the rifle.