This is a Pearce Grip Extension known as the Grip, model PG-30.
These units replace the magazine base plate and retain all other factory components. They do not alter the capacity of the magazine and they provide extra length for better control and comfort. This extension will also fit the Glock 30S. This extension will not fit the Glock M29 magazine.
Features:
High Impact Polymer
Increased Comfort and Control
Provides Magazine Identification
