This is the same Glock Factory Magazine extension used on the 33-round 9mm Big Stick magazine and the 22 round .40 caliber Big Stick magazine. It is also used on the new 19X 19-round magazine.
Add it to your magazine today to increase capacity of your standard full-size 9mm, .40 cal and .357 Sig magazines.
NOTE: This piece will fit on the 10 round factory magazines sold in California but it will not increase magazine capacity.
