Fab Defense S&W M&P 9 Shield +4 Magazine Extension - Black - This kit allows modifying the original 8 round magazine of the M&P Shield into a full capacity 12 round magazine, all this without having to replace the original magazine spring. + 4 Rounds For A Total Of 12 Rounds In The Magazine Innovative Spring Plate Design, Allows For The Use Of The Original Magazine Spring Enables A Full Grip On The Handgun Contoured Finger Indents For A Firm Grip During Magazine Manipulation Easy Installation, No Gunsmith Required Fiberglass Reinforced Polymer Construction