The Smith & Wesson M&P-15 Lower Receiver is a stripped AR-15 lower in 6061-T6 aluminum, finished in black. It ships without a trigger group, which is the point -- this is a build platform, not a complete rifle. 
 

Key Specifications 

• Caliber: 5.56 / .223 REM 
• Condition: New in Box 
• Finish Per Color: Black 
• Manufacturer: Smith and Wesson 
• Manufacturer Part Number: 812000 
• Model: M&P-15 Lower Receiver 
• Type: Lowers 
• UPC: 022188134193 
   

Features 

The lower uses mil-spec geometry and accepts standard AR-15 fire control groups, stocks, and pistol grips without modification. The 6061-T6 aluminum is lightweight and holds up to normal use. Fitment with some aftermarket uppers and parts can require minor fitting, which is typical of any stripped lower. 
 
This receiver suits anyone who wants to assemble a custom AR on an established, recognizable platform. Beginners get a straightforward starting point; experienced builders get a clean base for specific trigger and stock configurations.

Buyers generally regard the M&P-15 lower as a reliable, well-built starting point for an AR build. The mil-spec construction and compatibility with a wide range of uppers and accessories come up repeatedly as positives, along with smooth assembly and the general trust that comes with the S&W name.

Criticisms are modest. Some builders report minor fitment quirks with certain aftermarket parts, which is fairly common across stripped lowers in this category. A few users mention the black finish shows scratches over time. Those looking for more advanced machined features -- like integrated trigger guards or enhanced takedown pin holes -- may find higher-end options more satisfying, but for the price this lower gets the job done.